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Rale'.gh 


Inheritance  in  Poultry 


BY 


C.  B.  DAVENPORT 

DIRECTOR  OF  STATION  FOR  EXPERIMENTAL  EVOLUTIO 
COLD  SPRING  HARBOR,  NEW  YORK 


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WASHINGTON,  D.  C 
Published  by  the  Carnegie  Institution  of  Washington 

1906 


North  Carolina  State  Library 


Gift  of 


I 


North  Carolina  State  Library 


V/i  i  - 


Inheritance  in  Poultry 


BY 


C.  B.   DAVENPORT 

DIRECTOR  OF  STATION   FOR   EXPERIMENTAL  EVOLUTION, 
COLD  SPRING    HARBOR,  NEW  YORK 


WASHINGTON,  D.  C 
Published  by  the  Carnegie  Institution  of  Washington 

1906 


PUBLICATIONS  OF  THE  CARNEGIE  INSTITUTION  OF 

WASHINGTON,  No.  52 

PAPERS    OF  THE    STATION    FOR    EXPERIMENTAL 
EVOLUTION,  No.  7 


PRESS  OF 
JUDD  &   DETWEILER,  INC. 

WASHINGTON,  D.  C 


TABLE  OF  CONTENTS. 


Page 

A.  Statement  of  Problem i 

B.  Method  and  Material 5 

C.  Results  of  Crossing 6 

Series  I.  Single-comb  Black  Minorca  and 

White-crested  Black  Polish 6 

Statement  of  Problem 6 

The  Races  as  a  Whole 6 

Table  of  Characteristics 6 

Remarks  on  the  Characteristics 7 

I.  Comb,  7  ;  2.  Nostrils,  7  ;  3.  Form 
of  Skull,  S  ;  4.  Crest,  9  ;  5.  Color 
of  Crest,  10. 

Material 10 

Results 10 

I.  Comb,  10;  2.  Nostrils,  12;  3. 
Cerebral  Hernia,  13  ;  4.  Crest, 
14;  5.  Color  of  Top  of  Head,  15  ; 
6.  Correlation  of  Characters,  16. 

Conclusions 17 

Series  II.  Single-comb  White  Leghorn  and 

Houdan 18 

Statement  of  Problem 18 

The  Races  as  a  Whole i8 

Table  of  Characteristics 19 

Discussion  of  Characteristics 19 

I.  General  Plumage   Color,    19 ; 

2.  Color  of  Upper  Mandible,  19  ; 

3.  Nostrils,   19 ;     4.  Comb,    19 ; 

5.  Whiskers      or     Muff,     20 ; 

6.  Beard,  20  ;  7,  8.  Crest ;  Cere- 
bral Hernia,  20;  g.  Foot  Color, 
20  ;  10.  Number  of  loes,  20. 

Previous  Investigations 21 

Material 21 

Results 21 

I.  General  Plumage  Color,  21;  2. 
Color  of  Upper  Mandible,  22  ; 
3.  Nostrils,  22  ;  4.  Comb,  22 ;  5. 
Face  Feathering,  23  ;  6.  Beard, 
24;  7.  Cerebral  Hernia,  24;  8. 
Crest,  24  ;  9.  Foot  Color,  24  ;  10. 
Numberof  Toes,  25;  11.  Corre- 
lation of  Characters,  25. 

Conclusions 26 

Series  III.  Houdan  and  Single-comb  Black 

Minorca 27 

Statement  of  Problem  27 

The  Races  as  a  Whole 27 

Table  of  Characteristics 27 

Material 28 

Results 28 

I.  General  Plumage  Color,  28; 
2.  Comb,  28  ;  3.  Nostril  Form, 
28;  4.  Crest,  28  5.  Cerebral  Her- 
nia, 28  ;  6.  7.  Muff  and  Beard, 
28  ;  8.  Foot  Color,  28;  9.  Toes,  28. 
CouclUbions 28 


Page 

Series  IV.  Single-comb  White  Leghorn  and 

Rose-comb  Black  Minorca 29 

Statement  of  Problem 29 

The  Races  as  a  Whole 29 

Table  of  Characteristics 29 

Remarks  on  the  Characteristics 29 

I.  General  Plumage  Color,  29  ; 
2.  Comb  Form,  29;  3.  Foot 
Color,  29. 

Material 29 

Results 30 

1.  Plumage  Color,  30;  2.  Comb 
Form,  30  ;  3.  Foot  Color,  31. 

Conclusions 31 

Series  V.  Single-comb  Black  Minorca  and 

Dark  Brahma 31 

Statement  of  Problem 31 

The  Races  as  a  Whole 31 

Table  of  Characteristics 32 

Remarks  on  the  Characteristics 32 

I.  General  Plumage  Color,  32; 

2.  Wing  Bars,  32  ;  3.  Comb,  32  ; 
4.  Karlobe  Color,  33 ;  3.  Iris 
Color,   33  ;    6.  Foot  Color,  33 ; 

7.  Foot  Feathering,  34  ;  8.  Vul- 
ture Hock,  34. 

Material 34 

Results 34 

I.  General  Plumage  Color,  34  ;  2. 
Wing  Coverts,  35  ;  3.  Comb, 
35  ;  4.  Earlobe  Color,  35 ;  5.  Iris 
Color,  35 ;  6.  Beak  and  Foot 
Color,  35  ;  7.  Foot  Feathering, 
35  ;  8.  Vulture  Hock,  35. 

Conclusions 36 

Series    VI.     White    Leghorn    and     Dark 

Brahma 36 

Statement  of  Problem 36 

The  Races  as  a  Whole 36 

Table  of  Characteristics 36 

Remarks  on  the  Characteristics 36 

I.  Hackle  Color,  36;  3.  Wing 
Bow,  37. 

Material 37 

Results 37 

I.   General  Plumage  Color,  37; 

3.  Wing  Coloration,  37;  4.  Tail 
Color,  38  ;  5.  Comb  Form,  38  ;  6. 
Karlobe,  38;   7.  Iris  Color,  38; 

8.  Vulture  Hock,  38  ;  9.  Foot 
Feathering,  38. 

Conclusions .*...         38 

Series   VII.      Black    Cochin     Bantam    and 

White  Leghorn  Bantam 39 

Statement  of  Problem 39 

The  Races  as  a  Whole 39 

Table  of  Characteristics 39 


(III) 


IV 


TABLE    OF   CONTENTS. 


Page 

Remarks  on  the  Characteristics 39 

1.  Geueral  Plumage  Color,  39  ; 
2.  Earlobe  Color,  39  ;  3.  Vul- 
ture Hock,  39. 

Material 39 

Results 40 

I.  General  Plumage  Color,  40  ;  2. 
Earlobe  Color,  40  ;  3.  Vulture 
Hock,  40;  4.  Foot  Feathering, 
40. 

Conclusions 40 

Series  VIlI.   White  Le.^horu  Bantam  and 

Buff  Cochin  Bantam 40 

Statement  of  Problem 40 

The  Races  as  a  Whole 40 

Table  of  Characteristics 41 

Remarks  ou  the  Characteristics 41 

I.  General  Plumage  Color 41 

Material 42 

Results 42 

I.  General  Plumage  Color,  42  ;  2. 
Earlobe  Color,  43  ;  3.  Vulture 
Hock, 43;  4.  Foot  Feathering,43. 

Conclusions 43 

Series  IX.    Tosa    Fowl    (Yokohama)    and 

White  Cochin  Bantam 43 

Statement  of  Problem 43 

The  Races  as  a  Whole 43 

Tablt:  of  Characteristics 44 

Remarks  on  the  Characteristics 44 

I.  General  Plumage  Color,  44  ; 
2.  Tail,  44;  3-  Foot  Feather- 
ing, 48 ;    4.  Foot  Color,  48. 

Material 4S 

Results 49 

I.  General  Plumage  Color,  49  ; 
2.  Tail  Length,  49 ;  3.  Foot 
Feathering,  50  ;  4.  Foot  Color, 
50  ;  5.  Correlation  of  Character- 
istics, 51. 

Conclusions 51 

Series  X.  Dark  Brahma  and  Tosa  Fowl 51 

Statement  of  Problem 51 

The  Races  as  a  Whole 51 

Table  of  Characteristics 52 

Remarks  ou  the  Characteristics 52 

I.  Shafting,  52  ;  2.  Hackle  l^ac- 
iug,  52;  3-  Body  Lacing,  52; 
4.  Penciling,  53  ;  5.  Red  Wing- 
Bar,  53  ;  6.  White  Wing-Bows, 
53  ;  8.  White  Earlobe,  53  ;  9. 
Iris  Color,  53. 

Material 53 

Results 54 

I.  Shafting,  54;  2.  Hackle  Lac- 
«"!?.  54  ;  3-  Body  Lacing,  54  ; 
4.  Peuciliug,  54  ;  5.  Red  Wing- 
Bar,  54  ;  6.  White  Wing-Bow, 
54;  7-  Comb,  54;  8.  Earlobe 
Color,  54  ;  9.  Iris  Color,  54  ; 
10.  Foot  Color,  54;  II.  Vulture 
Hock,  54;  12.  Foot  Feathering, 
55  ;  13-  Tail  Feathers,  55- 


Page 

Conclusions 55 

Method  of  Inheritauce,  55  ;  Sex  in 
Inheritance,  55. 

Series  XI.  Frizzle  and  Silky 55 

Statement  of  Problem 55 

The  Races  as  a  Whole 55 

Table  of  Characteristics 57 

Remarks  ou  the  Characteristics 57 

I.  Plumage  Color,  57  ;  2.  Comb 
Form,  57;  3-5.  Feather  Form, 
57  ;  6.  Number  of  Toes,  59  ;  7. 
Skin  Color,  59. 

Material 59 

Results 59 

I.  Plumage  Color,  59  ;  2.  Comb, 
59;  3-5-  Curvingof  Shaft,  Barb 
Length,  and  Barb  Form,  59  ; 
6.  Numl)er  of  Toes,  60  ;  7.  Skin 
Color,  60  ;  8.  Crest,  60. 

Conclusions 60 

Series  XII.  Single-comb  White  Leghorn 
Bantam  and  Black-breasted  Red  Rump- 
less  Game 61 

Statement  of  Problem 61 

The  Races  as  a  Whole 61 

Table  of  Characteristics 61 

Remarks  on  the  Characteristics 61 

4.  Uropygium 61 

Material 62 

Results 62 

I.  General  Plumage  Color,  62  ;  2. 
Beak  Color,  63;  3.  Uropygium, 

63  ;  4.  Foot  Color,  63. 
Conclusions 63 

Series   XIII.    Black    Cochin    Bantam    and 

Black-breasted  Red  Rumples.s  Game 63 

Statement  of  Problem 63 

The  Races  as  a  Whole 63 

Table  of  Characteristics 63 

Material 63 

Results 64 

I.  General  Plumage  Color,  64;  2. 
Uropygium,  64;   3.  Iris  Color, 

64  ;  4.  Vulture  Hock,  64  ;  5.  Foot 
Feathering,  64. 

Conclusions 64 

D.  Geueral  Discussion 65 

Inheritance  of  Particular  Characteristics...  65 

Comb  Form 65 

Nostril  Form 68 

Cerebral  Hernia 69 

Crest 69 

Whiskers,  or  Muflf. 70 

Beard 70 

Feather  Form 70 

Uropygium 71 

Tail-Length 71 

Vulture  Hock 71 

Foot  Feathering 72 

Extra  Toes 72 

Skin  Color 73 

Mandible  Color 74 

Foot  Color 74 


TABLE   OF   CONTENTS. 


Page 

Iris  Color 74 

Earlobe  Color 74 

General  Plumage  Color 74 

White  vs.  Dark 75 

Dominance  of  White 75 

Barring 75 

Andalusian  Coloration 76 

White  vs.  Buff 76 

Black  z/j.  Red 76 

Color  of  Top  of  Head 76 

Color  of  Hackles — Hackle  I,acing 77 

Wing  Color— Red  Wing  Coverts 77 

Tail  Color 77 

Shafting 77 

Body  Lacing 78 

Penciling 78 

General  Topics  in  Inheritance 78 

Unit  Characters 78 

Alternative,  Particulate  (Mosaic),  and 

Blending  Inheritance 81 

Inheritance    of    Specific    vs.    Varietal 

Characteristics 82 

Inheritance  of  Positive    vs.   Negative 

Varietal  Characteristics 83 

Inheritance  of  Old  vs.  New  Character- 
istics   84 

Dominance  and  Recessiveness 84 


•  Page 

Dependence  of  Dominance  on  the  Races 

Crossed 86 

Prepotency  and  Dominance 87 

Hybrid  Forms 88 

Reversion 90 

Purity  of  Gametes 91 

Comparison  of  Reciprocal  Crosses 93 

Inheritance  of  Sexually  Dimorphic 
Characteristics  and  Sexual  Dimor- 
phism in  the  Hybrids 93 

Black  Minorca  and  Dark  Brahma...  94 

White  Leghorn  and  Dark  Hrahma..  94 

White  Leghorn  and  Houdan 94 

White    Leghorn     and     Rose-comb 

Black  Minorca 95 

Tosa  Fowl  and  White  Cochin  Ban- 
tam   95 

Dark   Brahma  (female)  and    Tosa 

Fowl  (male) 95 

Transfer  of  Sexually  Dimorphic  Char- 
acteristics from  One  Sex  to  the  Other.  95 

Sex  in  Hybrids 97 

Correlation  of  Characteristics 97 

The  Mutation  Theory  in  its  Relation  to 

the  Origin  of  Domesticated  Anima's..  98 

E.  Summary  of  Conclusions 100 

F.  Literature  Cited loi 


INHERITANCE  IN  POULTRY. 


By  C.  B.  Davenport. 


Evolution  proceeds  by  steps.  These  steps  are  measured  by  the  character- 
istics of  organisms.  When  in  the  evolution  of  a  race  a  characteristic  is 
added  a  progressive  step  is  taken.  When  a  characteristic  drops  out  a  retro- 
gressive step  is  made.  Since  the  characteristic  is  the  unit  of  evolution,  it 
deserves  careful  study.  The  present  work  is  a  first  study  of  the  method 
of  inheritance  of  characteristics. 

A.  STATEMENT  OF  PROBLEM. 

When  by  some  abnormal  process  a  single,  fertilized  egg  develops  into  two 
individuals  they  are,  and  continue  throughout  life  to  be,  almost  indistin- 
guishable. This  holds  true  even  when  the  conditions  of  life  of  the  two  are 
dissimilar.  This  case  is  exemplified  by  ' '  identical  twins ' '  as  they  occur  in 
man,*  The  great  similarity  of  such  identical  twins  teaches  that  environ- 
ment plays  a  small  part  in  determining  adult  characteristics  as  compared 
with  heredity.  Consequently  more  confidence  can  be  felt  that  the  results 
of  hybridization  experiments  are  directly  due  to  inheritance  ;  they  are  little 
affected  by  varying  environment. 

The  children  of  the  ordinary  family  are  not  identical  in  appearance, 
although  showing  marked  family  traits.  Certain  characteristics  may  be 
common,  but  others  are  peculiar  to  each  individual  child.  This  proves  that 
the  fertilized  eggs  of  the  same  two  parents  have  not  the  same  hereditary 
potentialities.  It  indicates  also  that  we  cannot  predict  the  characteristics 
of  the  offspring  from  those  of  the  parents.  The  proportion  of  qualities 
derived  from  either  one  of  the  two  parents  will  differ  in  different  children, 
or  new  qualities  may  appear.  This  is  because  the  offspring  do  not  inherit 
from  the  visible  part  of  the  parents'  bodies  but  from  their  hidden  germ 
cells  or  ' '  gametes. ' '  And  the  characteristics  of  the  soma  are  never  through- 
out the  same  as  those  of  the  ripe  gametes  it  carries. 

When  the  parents  belong  to  different  races  having  markedly  dissimilar 
characteristics  there  is  not  merely  the  question  of  dissimilarity  of  the  off- 
spring but  of  the  inheritance  of  the  antagonistic  characteristics.     Until 

*  Gallon,  F.,  1883,  pp.  216-243.     Compare  also  for  a  critical  study  of  resemblance  in 
twins,  Thorndike,  1905. 


2  INHERITANCE    IN    POULTRY. 

recently  the  law  has  been  commonly  accepted  which  is  thus  expressed  by 
Darwin  (1876,  Chapter  XV)  :  "When  two  breeds  are  crossed  their  char- 
acters usually  become  intimately  fused  together."  Many  cases  of  non- 
fusing  inheritance  are  now  known  and  it  is  important  to  ascertain  the  rela- 
tive frequency  of  the  different  kinds  of  inheritance  and  their  relation  to  one 
another. 

Lucas  (1850,  p.  194)  recognizes  three  methods  of  inheritance,  which  he 
calls  respectively  that  of  election,  of  mixture,  and  of  combination.  They 
are  thus  defined  :  Election  results  in  imprinting  on  some  or  all  parts  of  the 
organism  the  characteristics  of  the  father  exclusively  or  those  of  the  mother. 
Mixture  results  in  a  mixed  or  simultaneous  representation  of  the  father  and 
of  the  mother  on  some  or  all  of  the  parts  of  the  organism.  Its  extreme  is 
fusion  of  characteristics.  Combination  results  in  the  substitution  of  a  new 
characteristic  in  the  place  of  any  representative  in  a  part  or  over  the  whole 
of  the  organism.  This  new  characteristic  results  from  the  interaction  of 
the  two  antagonistic  ones  just  as  a  chemical  combination  often  differs  wholly 
from  the  elements  which  have  been  united  in  its  manufacture. 

Darwin  (1876,  Chapter  XV)  seems  to  recognize  only  two  classes  of  inherit- 
ance, yiz. ,  one  in  which  characteristics  blend  and  one  in  which  they  refuse 
to  blend.  Of  the  latter  class,  however,  there  are  two  cases  ;  either  the 
hybrid  receives  all  its  characters  from  one  of  its  parents  only,  or  the  hybrid 
receives  part  of  its  characters  from  one  parent,  the  rest  from  the  other. 

Nageli  (1884;  1898,  p.  17)  describes  the  different  forms  of  inheritance 
very  clearly,  thus  : 

In  the  idioplasm  of  a  germ  cell  arising  from  the  crossing  of  unlike  individuals  the 
micellar  rows  of  the  individual  Aulagen  have  sometimes  an  intermediate  constitution 
and  produce  characteristics  in  the  organism  which  are  intermediate  between  the  char- 
acteristics of  the  parents.  Sometimes  the  micellar  rows  derived  from  the  father  and  the 
mother  respectively  lie  side  by  side  interchanged  in  the  idioplasm  of  the  offspring  in 
distinct  groupings  and  may  reproduce  in  the  organism  their  respective  characteristics 
side  by  side,  or  onl)'  one  of  them  may  develop,  while  the  other  remains  latent.  (Clark's 
translation.) 

Galton  (1889,  pp.  7,  12,  14)  distinguishes  three  kinds  of  inheritance,  as 
follows:  (i)  Partiailate,  or  inheritance  "bit  by  bit,  this  element  from  one 
progenitor,  that  from  another  ;  "  (2)  blending,  as  in  human  skin  color  ;  this 
may  "be  none  the  less  'particulate'  in  its  origin,  but  the  result  may  be 
regarded  as  a  fine  mosaic  too  minute  for  its  elements  to  be  distinguished  in 
a  general  view;"  and  (3)  exclusive,  as  in  human  eye  color;  although 
"there  are  probably  no  heritages  that  perfectly  blend  or  that  absolutely 
exclude  one  another,  but  all  heritages  have  a  tendency  in  one  or  the  other 
direction,  and  the  tendency  is  often  a  very  strong  one." 

The  different  types  of  inheritance  are  thought  by  various  authors  to  be 
characteristic  of  particular  sorts  of  crossing.  Isidore  Geoff roy  St.-Hilaire 
insisted  ' '  that  the  transmission  of  characters  without  fusion  occurs  very 


STATEMENT   OF   PROBLEM.  3 

rarely  when  species  are  crossed."  De  Vries  (1905,  pp.  253,  280)  concludes 
that  blending  and  particulate  inheritance  of  qualities  characterize  the 
offspring  of  crossed  species,  whereas  an  alternative  inheritance  of  qualities 
is  characteristic  of  the  offspring  of  a  species  crossed  with  a  variety  *  or  of 
two  varieties  crossed  iiiter  se. 

In  the  case  of  alternative  inheritance  there  often  is  exhibited  an  extremely 
suggestive  phenomenon.  When  hybrids  showing  such  inheritance  are 
crossed  i7itcr  sc  there  is  a  segregation  of  the  various  alternative  character- 
istics into  different  individual  offspring.  This  is  the  discovery  of  Mendel 
(i866).t  The  attempt  has  naturally  been  made  to  generalize  Mendel's 
law — to  make  it  apply  universally.  In  my  own  study  the  applicability  of 
this  law  has  been  kept  constantly  in  mind. 


*  It  is  to  be  recalled  that  in  the  De  Vries  system  a  variety  differs  from  its  parent 
species  either  in  that  a  characteristic  of  the  species  has  become  latent  in  the  variety  or 
in  that  a  characteristic  vehicli  was  latent  in  the  species  has  reappeared  in  the  variety.  A 
new  species,  on  the  other  hand,  differs  from  its  parent  species  in  the  acquisition  of  one 
or  more  wholly  new  characteristics.  "In  normal  fertilization  and  in  the  intercrossing 
of  varieties  all  characters  are  paired."  Hence  the  paired  characters  struggle  together  in 
the  zygote  and  the  stronger  one  of  the  pair  dominates  or  covers  over  the  weaker  one. 
Thus  inheritance  is  alternative  or  exclusive.  "In  crosses  between  elementary  species 
the  differentiating  marks  are  not  mated."  Hence  there  is  no  such  struggle  between 
characteristics  ;  consequently  those  of  both  parents  reappear  in  the  offspring,  iuterdigi- 
tating. 

fThe  rediscovery  of  Mendel's  work  simultaneously  by  De  Vries  and  by  Correns  in 
1900  will  always  rank  as  one  of  the  interesting  coincidences  in  the  history  of  science. 
There  is  evidence  that  others  had  independently  discovered  this  law  in  their  own  work 
in  the  last  third  of  the  nineteenth  century,  but  the  history  of  this  law  is  still  to  be  written. 
I  may  note  that  Haacke,  in  1S93,  as  a  result  of  extensive  breeding  of  animals,  expresses 
the  law  of  purity  of  the  germ  cells.  He  has  the  theoretical  idea  that  inheritance  is  con- 
veyed both  by  the  plasma  (P)  and  the  nucleus  (Kern,  K).  In  the  union  of  dissimilar 
races  two  kinds  of  plasma  (P  and  P^)  and  two  kinds  of  nuclear  material  (K  and  K^)  may 
be  distinguished.     On  page  236  he  says  : 

Die  beideu  verschiedenen  Plasmen  P  und  P'  die  sich  bei  der  Befruchtuns  vereiuigt  haben,  trenuen 
sich  wieder  bei  der  Reductionsteiluug  der  Keimzelle,  uud  dasselbe  gilt  von  den  beiden  Kernstoffe  K 
und  K'.  Diese  Trennuiigist  in  manchen  Fallen,  wie  es  scheint,  eine  vollige,  so  dass  die  Plasmen  und 
die  Kernstoffe,  ab^esehen  von  den  mehr  oder  minder  weitgehenden,  aber  niemals  vollkommenen 
Ausgleichunsen  ihrer  Eigenschafien,  diedurch  gegeuseitige  Beeiufliissung  stattfinden  miissen,  ebeuso 
rein  aus  der  Vereiuigung  hervorgehen,  als  sie  in  diese  hineingetreten  sind. 

Still  further  Haacke  recognizes  that  in  the  separation  of  qualities  that  occur  in  the 
reduction  period  of  the  hybrid  germ  cells,  those  from  different  parents  may  gather  into 
one  germ  cell.  Since  this  occurs  in  accordance  with  the  laws  of  chance  (worked  out  in 
an  example  b}'  Haacke),  we  have  various  combinations  of  characteristics  in  the  second 
hybrid  generation.  Because  of  the  purity  of  the  germ  cells  it  will  often  happen  that 
mice  having  certain  qualities  will,  when  bred  together,  produce  only  those  qualities, 
however  complex  their  ancestry.  For  example,  white  dancing-mice  bred  together  will 
produce  nothing  but  white  dancing-mice.  Haacke's  results  seem  to  have  been  overlooked 
by  recent  experimenters. 


4  INHERITANCE    IN    POULTRY. 

In  typical  Meudelian  cases  not  only  do  the  qualities  segregate  in  the  second 
hybrid  generation,  but  in  addition,  in  the  first  generation,  when  two  con- 
trasted characteristics  are  bred  together  one  of  the  two  is  patent  in  the 
offspring ;  the  other  does  not  appear.  The  first  is  the  dominant  quality  ;  the 
second  is  recessive. 

It  seems  at  first  to  have  been  assumed  that  when  one  of  two  antagonistic 
characteristics  was  dominant  over  the  other  it  was  so  in  all  cases.  Recent 
studies  have,  however,  greatly  expanded  our  notion  of  dominance  and  reces- 
siveness.  Even  in  alternative  inheritance  we  have  to  admit  various  addi- 
tional phenomena  of  which  the  following  are  examples  :  Prepotency  of  a 
character,  elsewhere  recessive,  in  some  individual  or  strain.  Latency,  as 
Castle  (1905,  p.  24)  uses  the  term,  or  the  inactive  persistence  of  a  normally 
dominant  characteristic  in  a  recessive  individual  or  gamete.  When  the 
recessive  is  cross-bred  the  latent  characteristic  may  appear  as  a  dominant. 
Reversion,  or  the  assumption  of  an  atavistic  character  by  a  heterozygote. 
This  is  illustrated  by  the  case  of  the  cross  between  albino  and  black-and- 
white  mice  which  throw  gray.  However,  this  instance  may  be  one  of 
latency.     In  this  study  attention  will  be  paid  to  these  phenomena. 

What  determines  dominance  in  any  case  ?  This  is  a  disputed  point. 
De  Vries  (1905,  pp.  278,  280)  suggests  "  that  hybrids  between  a  species  and 
its  retrograde  variety  will  bear  the  aspect  of  the  species,"  and  "that  the 
older  character  dominates  the  younger  one."  However,  he  says  it  is  not 
the  systematic  relation  of  the  two  parents  of  a  cross  that  is  decisive,  but  only 
the  occurrence  of  the  same  quality,  in  the  one  in  an  active,  and  in  the  other 
in  an  inactive  condition.  Hence,  whenever  this  relation  occurs  between  the 
parents  of  a  cross  the  active  quality  prevails  in  the  hybrid,  even  when  the 
parents  differ  from  each  other  in  other  respects  so  as  to  be  distinguished  as 
systematic  species.  Correns  (1905)  also  cites  cases  in  which  the  active 
allelomorph  dominates.  In  my  studies  constant  attention  is  directed  toward 
this  matter. 

To  recapitulate  :  This  study  has  been  undertaken  to  determine  the  differ- 
ent forms  of  inheritance  (alternative,  particulate,  blending)  occurring  in 
poultry,  and  to  study  especially  the  phenomena  of  alternative  inheritance  as 
exhibited  in  this  group  in  order  to  see  in  how  far  they  accord  with  Mendel's 
law  and  in  how  far  the  accessory  phenomena  of  dominance,  latency,  and 
reversion  occur. 


METHOD   AND    MATERIAL.  5 

B.  METHOD  AND  MATERIAL. 

To  answer  in  the  shortest  time  the  foregoing  questions  about  inheritance 
it  was  necessary  to  use  some  rapid  and  fecund  breeder  and  to  interbreed 
both  varieties  and  species.  But  species-breeding  is  slower  and  more  diffi- 
cult and  not  more  important  than  breeding  races  ;  for  while  on  the  one  hand 
it  may  be  urged  that  races  are  artificial,  having  arisen  under  domestication, 
on  the  other  hand  hybridization  between  established  species  probably  plaj'S 
little  part  in  nature.  What  must  occur  again  and  again  in  nature  is  the 
mating  of  a  mutation  or  newly  arisen  race  with  the  parent  species.  It  has 
been  urged  that,  in  such  cases,  the  rare  mutation  must  be  swamped  by 
intercrossing  with  the  numerous  representatives  of  the  species.  But  if  new 
characters  do  not  blend  in  breeding  we  can  see  that  a  new  characteristic 
once  arisen  may  not  be  swamped.  Consequently  the  study  of  inheritance 
in  races  assumes  first  importance,  and  domestic  races  afford  the  best  material 
for  such  study. 

Again,  if  we  accept  the  doctrine  that  man  is  a  single  species,  all  the  mo- 
mentous questions  of  human  inheritance  are  questions  of  race  inheritance. 
The  outcome  of  such  an  admixture  of  races  as  is  going  on  in  America  is  a 
question  of  race  inheritance.  The  offspring  of  a  man  and  a  woman  having 
one  or  more  diverse  characteristics  will  follow  the  laws  deduced  from  a  study 
of  crossed  races.  These  are  practical  problems  of  human  evolution,  and 
experiments  made  with  domesticated  races  can  throw  light  upon  them. 

The  main  material  utilized  has  been,  as  stated,  poultry.  Poultry  offer 
these  great  advantages  :  That  they  are  easily  bred  in  great  numbers,  that  two 
generations  can  be  reared  to  maturity  in  a  year,  that  the}'-  stand  much 
inbreeding  without  loss  of  fertility,  and  that  the  number  of  well-defined 
characteristics  in  the  group  is  very  great. 

In  my  experiments  I  have  kept  29  pens,  each  with  its  cock  and  one  or 
more  hens.  To  separate  the  eggs  of  the  different  females,  trap  nests  were 
used  in  the  later  experiments  to  hold  the  hen  until  she  is  released.  Her 
number  is  read  and  written,  with  date,  upon  the  egg.  Before  placing  the 
eggs  in  the  incubator,  a  list  is  made  of  them.  Before  hatching,  eggs  of 
each  of  the  different  parentages  are  separated  into  a  compartment  by  them- 
selves, so  that  the  exact  parents  of  each  chick  may  be  known,  A  legband 
is  applied  to  the  chick  the  moment  it  is  removed  from  the  pedigree  tray  of 
the  incubator.  By  these  means  I  have  gained  in  one  year  1,500  offspring 
derived  from  known  parents,  and  have  reared  about  500  of  them  to  a  period 
when  their  adult  plumage  characters  were  distinguishable.  For  keeping 
records  I  have  used  a  field  pocketbook  and  a  day  book  at  my  work-table. 
"Loose  leaf"  forms  were  used  for  the  description  of  each  of  the  stock,  for 
its  egg  record,  for  a  chart  of  its  plumage,  and  for  its  photographs.  Finally, 
the  results  of  each  set  of  experiments  are  kept  in  a  large  book,  posted  nearly 
to  date. 


INHERITANCE   IN    POULTRY. 


In  treating  of  my  experiments  I  propose  first  to  give  the  results  by  the 
races  crossed,  and,  secondly,  to  discuss  in  order  the  problems  that  were  set 
at  the  beginning.  My  experiments  led  me  to  lay  little  stress  on  the  races 
as  named  by  fanciers.  In  fact  it  is  not  races  that  have  been  crossed  but 
characteristics.  However,  as  the  breeders'  names  have  a  utility  in  bringing 
to  the  mind  a  certain  combination  of  characteristics,  they  have  been  freely 
employed.  The  different  races  whose  offspring  are  discu-ssed  in  this  paper 
are  given  below  in  the  order  adopted  in  Wright's  Poultry  Book. 


Buff  Cochin  (Bantam). 
Biaik  Cochin  (Bantam). 
Dark  Brahma  (Bantam). 
Biack-breasted  Red  Game. 
Single-comb  Black  Minorca. 
Rose-comb  Black  Minorca. 
vSingle-comb  White  Leghorn. 


White-crested  Black  Polish. 

Houdan. 

Frizzle. 

Silky. 

Tosa  fowl,  or  Yokohama. 

Rumpless  Game  Bantam. 


C.  RESULTS  OF  CROSSING. 


Series 


-Single-comb  Black 


inorca  and  White-crested  Black  Polish. 
STATEMENT  OF  PROBLEM. 


The  cross  was  undertaken  primarily  to  learn  the  method  of  inheritance  of 
the  crest,  cerebral  hernia,  and  comb  of  the  remarkable  Polish  fowl. 

THE   RACES  AS  A   M'HOLH. 

The  Black-crested  White  Polish  (figs,  i  and  2)  belongs  to  a  class — Polish 
fowl — which  is  one  of  the  fundamental  types  of  poultry.  The  origin  of  the 
Polish  fowl  is  obscure.  They  were  mentioned  by  Aldrovandi  in  the  six- 
teenth centur)^  They  are  found  to-day  in  most  parts  of  the  world,  and  their 
most  characteristic  feature  may,  indeed,  have  originated  independently  many 
times.  This  feature  is  a  cerebral  hernia  and  its  associated  crest  of  large 
feathers. 

The  Single-comb  Black  Minorca  (figs.  3  and  4)  is  a  typical  representative 
of  the  Mediterranean  class  of  poultry — tall,  stately,  close-feathered,  non- 
broody  fowl, — modern  representatives  of  the  ancient  Egyptian  poultry. 
They  seem,  indeed,  to  have  come  from  Spain,  those  imported  to  England 
having,  according  to  Wright  (1902,  p.  391),  come  from  the  island  whose 
name  they  bear.     The  single  combed  form  is  the  original  and  typical  variety. 

TABLE  OF  CHARACTERISTICS. 


No. 

Characteristic. 

Single-comb  Black 
Minorca. 

White-crested  Black 
Polish. 

I 
2 

3 
4 

Comb 

Nostrils 

Top  of  head— skull.    

Top  of  head — plumage  form. . 
Top  of  head— plumage  color. 

Single,  very  large 

Narrow 

Normal 

Plain 

Two  papillae. 
Wide  or  high. 
Cerebral  hernia. 
Crested. 

5 

Black 

While  and  black. 

SINGI<E-COMB   MINORCA   AND   WHITE-CRESTED   POLI.SH.  7 

REMARKS  ON  THE  CHARACTERISTICS. 

1 .  Comb. — The  single  comb  of  the  Minorca  (fig.  4)  is  derived  from  the  primi- 
tive wild  ancestor,  for  all  the  four  feral  species  of  Gallus  have  a  single  comb. 
What  is  remarkable  about  the  comb  of  the  Minorca  is,  however,  its  enormous 
size,  gaining  in  many  fowls  a  length  of  150  mm.  and  a  height  of  100  mm. 
This  seems  to  have  been  brought  about  by  selection  of  extreme  variants  in 
fluctuating  variability  ;  at  any  rate,  English  breeders  have  gone  further  than 
American  breeders  have  thought  wise  in  the  production  of  enormous  combs. 

The  Polish  comb  (fig.  7,  PI.  II)  is  a  remarkable  structure  and  is  a  phylo- 
genetically  new  form.  Some  breeders  try  to  eliminate  it  altogether  ;  others 
retain  it  as  a  pair  of  horns.  I  quote  from  some  of  the  "Standards"  and 
descriptions  of  authors.  Mr.  P.  Jones  in  Tegetmeier  (1867,  p.  176)  says  : 
"There  should  be  no  appearance  of  comb."  Darwin  (1876,  Chapter  VII) 
says  :  ' '  Comb  absent  or  small  and  of  crescentic  shape. ' '  According  to  Wright 
(1902,  p.  443),  "  The  comb  should  be  practically  absent,  but  on  close  inspec- 
tion two  very  small  horns  can  generally  be  discerned."  Baldamus  (1896, 
p.  149)  states  :  "  Kamni  nicht  oder  kaum  bemerklich,  hochstens  2  kleine 
Spitzen  zulassig."  The  American  Standard  of  Perfection  (1905,  p.  152) 
announces  :  ' '  Comb  V-shaped,  of  small  size,  the  smaller  the  better  ;  set  evenly 
on  head,  retreating  into  crest ;  natural  absence  of  comb  is  preferred."  My 
parental  stock  (fig.  7)  had  two  large  papillae  of  irregular  form  and  large 
confluent  base.  Further  discussion  of  this  type  of  comb  will  be  deferred  to 
page  65. 

2.  Nostrils. — In  the  Minorca,  as  in  the  Jungle  fowl,  each  of  the  external 
nares  is  a  horizontal  slit  bounded  above  and  laterally  by  a  fold  of  cornified 
skin  (compare  fig.  22).  The  slit  leads  into  the  outer  ethmoid  cavity.  By 
removing  the  membrane  the  outer  fold  of  the  ethmoid  can  be  seen  as  a  ridge 
that  extends  well  distad  (Fig.  A).     In  the  Polish  fowl  the  outer  membrane 


o.e. 


12  3 

Fig.  a. — I.  Cross-sectiou  of  beak  of  Polish  fowl  through  wide  nostril; 
o.  <?.,  outer  ethmoidal  fold.  2.  Cross-sectiou  of  beak  of  Minorca  fowl  through 
narrow  nostril ;  p.  ;«.,  preraaxillary  bone  ;  «,  nasal  bone.  3.  Cross-section 
of  beak  of  fowl  behind  nostril  ;  o.  <■.,  outer  ethmoidal  fold. 

is  SO  short  that  the  narial  aperture  is  very  wide  and  the  outer  ethmoidal  fold  is 
exposed  to  view.  The  no.stril  may  be  said  to  be  wide  or  "  high  "  (figs.  7,  12). 
Sometimes  the  upper  margin  of  the  nostril  may  even  be  elevated  above  the 
level  of  the  culmen  of  the  beak,  and  in  this  case  a  transverse  fold  crosses  the 
culmen  from  nostril  to  nostril.     This  I  call  the  culminal  fold. 

The  morphology  of  the  nostril  of  the  Polish  fowl  seems  to  be  little  under- 
stood.    The  term  "cavernous"   is  applied  to  this  form  by  the  American 


8  INHERITANCE    IN   POULTRY. 

Standard  of  Perfection  (1905,  p.  13),  which  speaks  of  the  hollow  protruding 
nostrils.  Wright  (1902,  p.  441)  in  treating  of  the  cranial  dome  says  : 
' '  Excess  in  one  part  being  often  connected  with  defect  in  some  other,  as 
Mr.  Darwin  pointed  out,  the  skulls  with  this  peculiaritj'  usuallj'  show  a 
chasm  in  the  iutermaxillar}-  bones,  which  in  other  fowls  support  the  roof  of 
the  nostrils  ;  owing  to  which  deficiency  in  bony  support  the  nostrils  of  all 
heavily  crested  fowls  appear  flattened  and  depressed  and  yet  cavernous  in 
character. ' '  Darwin  ( i S76,  Chapter  VII)  attributes  the  width  of  the  nostrils 
to  the  circumstance  that  the  branches  of  the  premaxillary  and  of  the  inner 
processes  of  the  nasal  bone  are  somewhat  upturned. 

Comparing  the  skull  of  a  Polish  fowl  with  that  of  a  Minorca,  I  find  the 
following  relations  : 

First,  the  nasal  bone  has  in  the  Minorca  as  in  most  other  fowl  the  form  of 
the  Greek  ^- ;  the  single  stem  (processus  frontalis)  projects  caudad  and  lies 
as  a  flat  plate  above  the  frontal  bone  by  which,  also,  it  is  cut  off  from  contact 
with  most  of  the  lachrymal  bone.  The  two  anterior  branches  enclose  between 
them  the  olfactory  space.  The  processus  maxillaris  runs  nearly  perpendic- 
ular to  the  maxillary  bone  ;  the  processus  premaxillaris  is  a  slender  stylet 
terminating  over  the  middle  of  the  olfactory  space  and  embracing  the  nasal 
process  of  the  premaxillarj'  bone  (Fig.  A,  2,  n).  In  the  Polish  fowl  the  pro- 
cessus frontalis  is  relatively  shorter  and  broader.  The  whole  central  nasal 
area  is  greatly  depressed,  forming  a  cavity  in  front  of  the  cranial  dome — a 
cavity  that  is  filled  with  the  cartilaginous  foundation  of  the  rudimentary 
comb.  In  front  of  this  depression  of  the  skull  the  processus  premaxillaris 
rises,  reaching  about  the  normal  height  of  this  part  of  the  nasal  bone,  and 
stops  there  in  the  posterior  quarter  of  the  nasal  space.  Thus  the  bony 
nasal  space  is  posteriorly  of  normal  height.  What  is  peculiar  in  the  skull 
of  the  Polish  fowl  is  that  the  processes  premaxillaris  are  very  short  and  slender 
and  do  not  embrace  the  nasal  process  of  the  premaxillary,  but  instead  the 
cartilaginous  dorsal  edge  of  the  orbitosphenoid  or  mesethmoid.  This  thick- 
ened dorsal  edge  continues  anteriorly  as  the  edge  of  the  internasal  septum ,  and 
it  replaces  the  nasal  processes  of  the  premaxillary.  Anteriorlj'  the  septum 
abuts  upon  the  premaxillarJ^  At  this  point  there  is  adhering  to  the  premax- 
illary a  mass  of  tissue  in  the  median  plane  which  seems  to  be  the  rudiment 
of  the  nasal  process  of  the  premaxillary. 

In  criticism  of  Darwin's  explanation  of  the  wide  nostril  based  on  the  ground 
that  the  nasal  process  is  upturned,  it  ma}^  be  said  that  the  wide  nostril  lies  in 
front  of  the  upturned  nasal  bone  and  in  a  part  of  the  nasal  space  that  is  not 
higher  (nor  wider)  than  in  the  normal  skull.  I  think  it  must  be  concluded 
that  the  wide  nostril  is  independent  of  the  width  of  the  nasal  space.  As  we 
shall  see  later,  the  wide  nostril  is  never  found  in  connection  with  a  single  comb. 

3.  Form  of  Skull. — Polish  fowl  have  long  been  noted  for  the  remarkable 
form  of  their  skull.     This  was  referred  to  by  Bovelli  (1670,  cent.  2,  p.  157, 


SINGLS-COMB   MINORCA   AND   WHITR-CRESTED   POI.ISH.  9 

teste  Hagenbach)  and  has  been  studied  b}^  Blumenbach  (181 2),  Hagenbach 
(1839),  Tegetmeier  (1856),  Darwin  (1876),  and  others.  A  dome  rises  from 
the  front  of  the  nasal  bone  often  to  a  height  of  15  or  18  cm.  (figs.  7,  10, 
PL  II).  This  dome  is  the  secondary  bony  covering  of  a  cerebral  hernia 
whose  dura  mater  has  become  ossified.  Such  cerebral  hernias  are  not  un- 
common among  poultr^^  Roughly,  i  per  cent  of  the  chicks  (outside  of  the 
crested  races)  that  failed  to  hatch  in  my  incubations  and  were  examined  by 
me  had  such  a  hernia.  In  one  or  two  instances  Polish  chicks  that  died 
before  hatching  were  affected  by  incomplete  closure  of  the  cerebrum,  the 
top  of  the  head  not  being  covered  by  bone  or  skin.  Such  an  abnormality 
has  been  described  by  Hagenbach  (1839,  pp.  324-326)  also.  So  profound  a 
modification  of  the  brain  would  naturally  be  associated  with  mental  pecul- 
iarities. My  own  Polish  have  shown  themselves  very  slow  of  movement, 
and  two  male  Houdans  (having  the  same  sort  of  abnormal  skull)  were 
affected  by  some  trouble  in  the  head  which  led  them  to  move  backward, 
turn  somersaults,  and  move  otherwise  abnormally.  Hagenbach  states  that 
the  Polish  fowl  are  subject  to  apoplexy  and  epilepsy.  It  is  remarkable 
that  formerly  the  hens  alone  had  the  cerebral  hernia  (Darwin,  1876,  Chap. 
VII),  while  now  it  occurs  in  both  sexes. 

4.  Crest. — This  consists  of  a  number  of  large  white  feathers  arising  from 
the  frontal  region  of  the  skull  (figs,  i,  2,  and  7).  Structurally,  they,  like 
normal  feathers  from  the  top  of  the  head,  have  the  barbules  of  the  distal 
portion  of  the  barbs  reduced  so  that  the  barbs  do  not  interlock.  This  con- 
dition is  seen  in  the  hackles  of  all  breeds.  The  form  of  the  feathers  resem- 
bles that  of  the  hackle,  being  more  attenuated  in  the  male  than  the  female. 
The  great  size  of  the  crest  feather,  like  that  of  the  hackle,  is  largely  due  to 
its  long  period  of  growth.  After  molting,  the  new  crest  feathers  are  char- 
acterized by  long  and  stout  sheaths  in  which  the  feather  develops.  These 
persist  after  most  of  the  other  contour  feathers  no  longer  possess  sheaths 
and  consequently  have  stopped  growing. 

The  cause  of  the  crest  is  a  matter  of  much  interest.  Hagenbach  (1839, 
p.  329)  raises  the  question  and  says  : 

Niclit  ohne  Bedeutung  scheint  mir  iibrigens  eine  auf  die  Hemicephalie  beziigliche 
Beobachtung  von  Meckel*  zu  sein,  welche  so  lautet  :  "  Sehr  merkwiirdig  ist  die  haufig 
vorkommende  regelwidrige  starke  Entwicklung  von  Haaren  an  ungewohnten  Stellen. 
So  finde  ich  bei  einigen  von  denen,  welche  ich  vor  mir  habe,  und  gerade  bei  denen,  wo 
der  Hauptmaiigel  am  grossten  ist,  fast  den  ganzen  Korper,  besonders  aber  den  Riicken, 
die  Hiiften  und  die  obern  Extremitiiten,  mit  Haaren  von  6  Linien  bedeckt." 

Whether  or  not  the  developmental  disturbance  is  the  cause  of  the  pro- 
longed growth  of  feathers,  it  is  certain  that  the  immediate  cause  is  the 
unusual  and  prolonged  nutrition  of  the  feathers.  The  skin  from  which  they 
arise  is  thick  and  rich  in  blood-vessels.     Whether  the  cerebral  hernia  is  a 

*Handbucli  der  pathologischen  Anatomic,  Tom.  I,  p.  195-260. 


lO  INHERITANCE   IN   POULTRY. 

necessary  antecedent  of  the  increased  nutrition  of  the  feathers  or  not  can  be 
tested  by  hybridization,  which  will  show  whether  or  not  crest  and  dome  are 
absolutely  correlated. 

5.  Color  of  Crest. — In  our  race  this  is  white,  in  striking  contrast  with 
the  rest  of  the  plumage.  This  color  is  not  necessarily  associated  with  the 
crest.  Wholly  gold-spangled,  silver-spangled,  buff,  white,  and  even  black 
Polish  have  been  created.  On  the  other  hand,  since  normal  poultry  with  the 
top  only  of  the  head  white  are  unknown,  it  seems  probable  that  the  color  of 
the  crest  has  dissociated  itself  from  that  of  the  other  parts  of  the  body  as  an 
independent  unit  character.  Consequently  it  is  not  strange  to  find  a  black- 
crested  white  breed  of  Polish  (Wright,  1902,  p.  448).  It  will  be  of  interest 
in  our  experiments  to  see  how  far  color  and  crest  are  dissociable. 

MATERIAL. 

The  mothers  in  this  experiment  were  partly  Polish,  partly  Minorca.  The 
Polish  mothers,  Nos.  6  and  7,*  were  good  representatives  of  their  breed, 
with  perfectly  black  plumage  except  for  the  well-developed  white  crest. 
The  Minorca  mothers,  Nos.  13  and  14,  were  also  typical  birds  without  trace 
of  mealiness  in  feathers. 

The  father  Minorca  (No.  12,  fig.  4)  had  a  great  red  comb,  150  mm.  long, 
with  seven  points,  one  of  which  rose  to  100  mm.  above  the  level  of  the 
head.  Its  plumage  was  perfectly'  black.  The  paternal  Polish  (fig.  2)  had 
as  representative  of  the  comb  a  pair  of  papillae.  The  crest  anteriorly  con- 
tained some  black  feathers  with  white  base  or  tip  ;  next  came  feathers  75  to 
100  mm.  long,  at  first  largely,  then  wholly  white.  At  the  posterior  end  of 
the  crest,  where  it  passes  into  the  nape,  black  gradually  makes  its  appearance 
until  the  exclusively  black  feathers  of  the  neck  are  reached.  White  and 
black  do  not  blend  on  any  feather,  but  coexist  in  z.  particulate  fashion. 

RESULTS. 

I.  Comb. — First  generation.  Of  88  hybrids  between  single-combed  and 
Polish-combed  all  follow  a  single  type,  which  is,  however,  very  variable. 
The  comb  is  single  anteriorly  but  bifurcated  behind.  This  may  be  called 
the  Y-shaped  comb.  The  point  of  splitting  occupies  a  variety  of  positions. 
Usually  it  lies  in  the  middle  third  of  the  whole  comb  (fig.  8).  In  some 
cases,  such  as  Nos.  67^  (fig.  8),  1769,  3509,  and  4089,  the  splitting 
point  is  close  to  the  anterior  end,  so  that  the  comb  is  cup-shaped. f  In  other 
cases  the  point  of  division  may  be  so  far  posteriad  that  only  the  last  or  the 
last  few  serrations  are  split.  Indeed,  in  one  case  (No.  324,  which  died  five 
weeks  after  hatching),  the  comb  was  apparently  perfectly  single.  I  regard 
this  as  the  last  term  of  the  series  and  suspect  that  there  existed,  even  in  this 

♦Bought  July  I,  1904;  No.  7  die* October  17,  1904. 

t  Such  ji  comb  is  mentioned  by  Darwin  (1876,  Chap.  VII)  as  formed  when  the  two  ends 
of  a  double  comb  are  cemented  together. 


SINGI<K-COMB   MINORCA   AND   WHITE-CRESTED    POIvISH, 


II 


case,  a  repressed  potentiality  toward  splitting  of  the  comb  at  its  posterior  end. 
In  general,  then,  the  hybrid  condition  between  single  comb  and  supranasal 
papillae  is  a  Y-shaped  comb*  and  there  is  an  absence  of  dominance. 

Second  getia'ation .     When  the  birds  with  Y-shaped  combs  were  interbred 
the  loi  offspring  were  of  three  types,  as  follows  : 


Characteristic. 

No.  of 
individuals. 

Percentages. 

Actual. 

Expected. 

Single  comb 

30 
47 

24 

29.7 

46.5 
23.8 

a 

25 
50 
25 

18.75 
56- 25 
25.00 

Cleft  comb 

Papillse  or  "  absent " 

Total 

lOI 

ICO.O 

100 

100.00 

Kxpectation  in  this  case  depends  on  the  theoretical  view  we  take  of  the 
nature  of  the  unit  characters  involved.  We  may  assume  that  single  comb  and 
V-comb  are  the  allelomorphs  and  split  comb  a  heterozygous  type,  constantly 
reproducing  itself.  On  this  assumption  we  should  expect  the  proportion 
given  in  column  a  of  the  foregoing  table.  On  the  other  hand,  following  the 
method  of  interpretation  suggested  by  Cuenot  (1903)  and  Correns  (1905)  in 
such  cases,  we  may  assume  two  pairs  of  allelomorphs,  namely,  (la)  median 
comb  and  {ib)  no  median,  and  (2a)  no  splitting  and  {2b)  splitting.  Taking 
median  comb  and  splitting  as  dominant,  the  single  comb  combines  the  two 
characters  :  median  comb,  no  splitting  ;  the  V  comb  combines  :  no  median 
comb,  splitting.  In  generation  Fj  the  four  characters  are  combined  :  median 
(no  median),  splitting  (no  splitting),  and  the  comb  is  Y-shaped,  the  char- 
acteristics put  in  parenthesis  being  recessive.  The  F^  generation  follows 
the  law  of  inheritance  in  dihybrids  : 

Per  cent. 

C splitting  X  splitting ^'^  I  tS3/ %       (a\ 

)..\2  ^Splitting  X  no-splitting)  ..    12^2  /  ^^'+  /"  ■  '  ^'^l 


25  %  {Median  X  median). 


(  'So-Splitting  X  no-splitting. .     6%. 

^ Splitting  X  splitting \2]A 

25 

12>^ 


50  J.     [Median    X     "0-'«^- J  ^'(^^/zVf/^a- x  no-^///^^^^^^ 
"^^") i No-splitting  X  no-splitting. 


}  37/2%. 


.   ,^T  ,.       ^,  ( Splittim:  y.  splitting-    ^%  \  ro.^/ & 

25  %  {^o-medtan  X  "o-/«^- I    ^,^^^,7^ •„,.  ^  ^o-splitting)  ..   i2>^  j  '^'^>- 

"^^" ) i  'No-splitting  X  no-splitting. .. 


ass. 

Relative 
frequency 

(a) 

3 

{b) 

I 

\c, 

6 

{d) 

2 

{e) 

3 

(/) 

I 

Summing  up,  out  of  every  16  individuals  we  should  expect: 


Characteristic  and  class. 

Relative 
frequency. 

Per  cent. 

Median  and  solit  comb  ia]  -\-  ic] 

9 

3 
3 
I 

56.25 

18.75 

}    25.00 

Median  and  unsplit  comb  {b)-\-{d) . .    . .    

No-median  and  split  comb  [e) 

No-median  and  no-split  comb  [/) 

*  For  further  discussion  of  the  y-shaped  comb  see  page  65. 


12 


INHBRITANCE    IN    POULTRY. 


On  account  of  the  difficulty  of  deciding  iu  the  case  of  any  young  chicks 
whether  '  no-median  and  no-sphc  comb  '  is  present,  the  last  two  classes  are 
combined  in  the  right-hand  column  of  this  table  and  in  columns  a  and/3  of  the 
table  above. 

In  comparing  the  fit  of  the  expected  percentages  on  the  two  hypotheses 
with  the  actual,  it  is  seen  that  hypothesis  a  is  the  better.  However,  the  real 
test  will  come  in  the  F3  generation.  On  hypothesis  a  the  single-combed 
individuals  bred  together  should  produce  only  median-combed  offspring.  On 
hypothesis  ?  they  should  produce  some  without  median  comb.* 

First  generation  hybrids  crossed  with  Minorca.  When  the  Y-shaped  comb  is 
crossed  back  on  the  single  comb  of  the  Minorca  (No.  26  c?  )  the  following 
distribution  of  comb  characters  was  obtained  : 


Characteristic. 


Single  comb 

Cleft  comb 

Papillae  or  "absent 


Frequency.    Per  cent. 


21 

ti9 
o 


52.5 

47-5 
0.0 


This  result  accords  well  with  the  expectation  that  50  per  cent  of  the 
combs  shall  be  of  the  pure  Minorca  type  and  50  per  cent  of  the  heterozy- 
gous type. 

2.  Nostrils. — First  generation.  No  case  occurred  of  a  typical  high  nostril; 
this  characteristic  is  dominated  by  the  narrow  nostril  ;  but  this  dominance 
is  imperfect.  In  three  cases  (5  per  cent)  the  nostril  is  recorded  as  one-half 
high,  /.  e.,  having  an  aperture  one-half  as  high  as  the  extreme.  In  the 
other  cases,  placed  in  class  2,  the  breadth  w^as  less,  but  still  evidently  influ- 
enced by  the  germinal  representative  of  the  ' '  high  ' '  characteristic.  In  two 
skulls  that  were  dissected  the  processus  nasalis  of  the  premaxillary  bone 
was  present. 


class. 


Characteristic. 


Narrow 

a.  One-third  high 7 

b.  One-half  high 3 

High 


Total  . 


First  generation. 

Class. 

/• 

Per  cent. 

47 

}     ^° 

0 

83 

17 

0 

I 
3 

- 

100 

Characteristic. 


Narrow 

a.  One-third  high 16 

b.  One-half  high 6 

High  or  nearly  high.... 

Total 


Second  generation. 


f.  Per  cent. 


45 
22 
18 


85 


529 
25-9 
21.2 


100. 0 


Second  generation.   In  the  second  generation  the  high  nostril  appears  again 
in  full  or  nearly  full  size  in  21  per  cent  of  the  cases.     Class  3  includes  two 


*This  topic  is  discussed  again,  generally,  at  page  68. 

t  Including  one  thick  comb  with  a  median  ridge  in  addition  to  the  cleft  comb,  forming 

103. 


a  typical  pea  comb.     Seen  in  unhatched  chick  XVIII, 


SINGLE-COMB   MINORCA    AND    WHITE-CRESTED   POLISH. 


13 


cases  in  which  the  records  read  three- fourths  high  ;  but  even  in  the  PoUsh 
fowl  the  high  nostril  varies  somewhat.  Theoretically,  we  should  expect  25 
per  cent  of  the  second  generation  to  have  the  recessive  high  nostril.  The 
deficiency  may  indicate  merely  insufficient  numbers,  or  perhaps  some  of 
the  "  one-half  high  "  group  truly  belong  in  "  class  3."  The  essential  facts 
are,  first,  that  high  and  narrow  are  segregated,  and  that  in  the  second 
generation  also  dominance  is  frequently  imperfect. 

First  generatioyi  hybrid  crossed  "with  Minorca.  The  heterozygous  mothers  all 
had  narrow  nostrils,  as  of  course  had  the  Minorca  father.  No  true  case  of 
high  nostril  occurred.     The  recorded  distribution  is  as  follows  : 


Class. 

Nostril. 

No  of 
individuals. 

I 
2 

Narrow. ...        

12 
13 

One-third  to  one-half  hisrh 

It  seems  probable  that  the  1 2  individuals  with  narrow  nostrils  belong  to 
homogametous  birds  and  the  13  individuals  of  class  2  to  heterogametous 
birds. 

3.  Cerebral  Hernia.  — First  hybrid  generation.  Every  bird  was  without  a 
typical  cerebral  hernia.  Nevertheless  some  of  them  showed  clear  traces  of 
their  mixed  ancestry.  On  the  frontal  bone  of  all  fowl  is  the  so-called 
frontal  eminence  which  is  covered  by  fascia  and  the  thickened  skin  of  the 
crest.  The  profile  of  the  skull  from  the  apex  of  this  eminence  to  the 
parietal  is  nearly  straight,  except  for  a  slight  concavity  limiting  the  frontal 
eminence.  In  hybrids  this  concavity  is  frequently  still  more  marked,  the 
eminence  being  higher.  Indeed,  in  one  case  (No.  405  9  )  the  concavity  is 
so  marked  that,  as  far  as  one  can  judge  from  the  living  bird,  there  is  a 
slight  hernia.  We  see,  then,  that  though  plain  head  is  dominant  it  is  incom- 
pletely so. 

Second  hybrid  generation.  The  following  is  the  distribution  of  this  char- 
acteristic when  the  hybrids  are  bred  i7iter  se.  Expectation  is:  75  per  cent 
without  hernia,  25  per  cent  with  hernia.  The  result  agrees  closely  with 
expectation. 


Characteristic. 


Hernia  absent. 
Hernia  present 

Total   .. 


Frequency. 


75 
23 


98 


Per  cent. 


76.5 

23-5 


lOO.O 


First  hybrid  generation  crossed  with  Minorca.  Since  the  first  generation  is 
DR  and  Minorca  is  D,  half  of  the  offspring  will  be  pure  dominants  and  half 


14 


INHERITANCK    liN    POULTRY. 


heterozygous,  both    halves   showing    the    domiuaut  "absence  of  hernia." 
The  result  agrees  with  expectation. 


Characteristic. 

Frequency. 

Per  cent. 

Hernia  absent 

^4 

TOO 

Hernia  oresent 

'i         ::: 

Total 

34 

1 

4.  Crest. — First  hybrid  generation.  The  crest  is  present  in  every  hybrid 
old  enough  to  show  a  crest,  yet  always  in  reduced  size.  Crest  is  dominant, 
but  the  dominance  is  imperfect.  The  crest  is  larger  in  the  females  (fig.  5) 
than  in  the  males  (fig.  6). 


Characteristic. 

Frequency. 

Per  cent. 

Crest  absent 

Crest  present 

Total 

0 

70 

0 

100 

70 

Secojid  hybrid  generation.     All  records,   from  embryo  chicks  as   well  as 
adults,  give  : 


Characteristic. 

Frequency. 

Per  cent. 

Crest  absent 

23 
52 

*3o.7 
693 

Crest  present 

Total 

75 

loo.o 

*Fig.  II. 

Expectation  is  that  crest  will  be  absent  in  25  per  cent  of  the  cases.  The 
excess  is  probably  due  to  the  fact  that,  since  crest  develops  late,  it  was  noted 
as  absent  when  it  would  have  appeared  in  adtilt  life.  To  test  this  I  give  a 
table  based  on  hatched  chicks  only  : 


Characteristic. 

Frequency. 

Per  cent. 

Crest  absent 

II 

41 

21.2 

78.8 

Crest  present 

Total 

52 

lOO.O 

This  gives  a  close  approximation  to  expectation,  with  a  slight  excess  of 
crested  individuals.     The  exact  statistical  proportion,  with  its  possible  errors 


SINGIvE-COMB    MINORCA.    AND    WHITE-CRESTED    POLISH. 


15 


of  cla.ssification,  is  less  essential  than  the  fact  of  reappearance  in  about  one- 
fourth  of  the  cases  of  the  recessive  characteristic. 

First  hybrid  generation  crossed  with  Minorca.  Since  plain-head  is  R,  the 
cross  is  of  the  order  DR  X  R  ;  from  which  we  should  expect  an  equal  number 
of  heterozygous  (crested)  and  pure  recessive  (plain-headed)  offspring.  The 
result,  though  based  on  small  numbers,  accords  with  expectation. 


Characteristic. 


Crest  absent  (RR). 
Crest  present  (DR) 

Total.. 


All  records. 


12 

8 


Hatched 
chicks  only. 


6 
6 


20 


12 


5.  Color  op  Top  of  Head. — First  hybrid  generation.    All  records  give  : 


Characteristic. 


Wholly  black . . 
Black  and  white 

Total  .... 


Frequency. 


36 
20 


Per  cent. 


64-3 
35-7 


56 


loo.o 


It  is  to  be  noted,  first,  that  the  white  of  the  crest  tends  to  disappear  in  the 
later  molts,  some  birds  which  showed  it  at  2  months  losing  it  by  6  months, 
or  showing  white  at  the  tip  only  of  the  crest  feathers.  Further,  with  two 
exceptions,  all  crests  with  white  feathers  belong  to  females  (which  have 
larger  crests  than  males).  The  two  exceptional  males  are  still  young  and 
have  only  a  trace  of  white  remaining  ;  this  will  probably  disappear  in  the 
next  molt.  Third,  the  proportion  of  white  to  black  in  the  crest  is  always 
small — much  smaller  than  iu  the  Polish  crest.  Tne  result  looks  like  an 
imperfect  dominance  of  black. 

Second  hybrid  generation.     Hatched  chicks  only  give  : 


Characteristic. 


Wholly  black  . .  . 
Black  and  white. 

Total     .    .  . 


Frequency.       Per  cent. 


24 
27 


47.1 
529 


51 


loo.o 


I  interpret  this  irregular  result  to  be  due  to  the  imperfect  dominance  of 
black.  Twenty-five  per  cent  of  the  individuals  have  wholly  black  gametes 
and  25  per  cent  wholly  black-and-white,  or  mosaic,  gametes.  The  50  per 
cent  with  mixed  gametes  tend  to  be  black,  but  contain  white  in  varying  pro- 
portions. Something  more  than  one-fourth  of  the  black-and-white  headed 
individuals  are  males. 


1 6  INHERITAXCK    IN    POULTRY. 

First  hybrid  crossed  with  Minorca.     All  records  give  : 


Characteristic. 

Frequency. 

Per  cent. 

Wholly  black   

21 
2 

91-3 

8.7 

Black  and  white 

Total 

23 

lOO.O 

Expectation,  assuming  complete  dominance  of  black,  is  lOO  per  cent  of 
black  individuals.  Result  shows  incomplete  dominance.  Of  the  black-and- 
white  headed  individuals,  one  is  a  female  ;  the  other  died  too  early  for  the 
sex  to  be  determined.     Here,  again,  dominance  is  less  perfect  in  the  female. 

6.  Correlation  of  Characters. — In  the  Single-comb  Black  Minorca 
and  in  the  White- crested  Black  Polish  there  is  an  assemblage  of  characters 
that  are  nearly  always  associated  in  those  races.  The  first  hybrids  have 
another  constant  association  unlike  either  of  the  parents,  viz.,  split  comb, 
black  crest  (in  the  male)  without  cerebral  hernia,  and  low  to  medium  nos- 
trils (fig.  6).  In  the  second  generation  of  hybrids,  on  the  other  hand,  occur 
combinations  of  characters  both  of  the  parental  species  and  also  of  the  first 
generation  of  hybrids.  These  combinations  are  of  the  most  varied  sort,  so 
that  characteristics  always  found  associated  in  one  parent  species  may  here 
be  found  dissociated.  When  hybrids  are  bred  i>iter  se  the  following  com- 
binations are  obtained  : 


No.   1 

Comb. 

I 

^       c 

2 

j 

3     i 

' 

4 

r    Y 

1 

5     1 

1 

6     i 

7 

8 

J 

9 

1 

lO 

1 

II 

12 

13 

1     - 

14 

1 

15    ; 

1 

i6 

J 

1 

17     i 

" 

i8     1 

19 

20 

-    O  0     . 

21 

1 

22 

23 

i 

24 

J 

Crest. 


Present . 
Absent 
Present . 
Absent  . 
Pre.'eut. 
Absent  . 
Present 
Absent  . 
Present . 
Absent  . 
Present . 
Absent  . 


Hernia. 


Nostril. 


Absent  . 
Absent  . 
Present 
Present. 
Absent  . 
Absent  . 
Present . 
Present. 
Absent  . 
Absent  . 
Present. 
;  Present. 


■{ 


Narrow. 

High... 

Narrow . 
\  High... 
f  :  Narrow. 
I  High... 
f  !  Narrow, 
t  High... 
f  Narrow. 
\  !  High  . .  . 
/     Narrow . 

High   . 

Narrow . 

High... 

Narrow . 

High... 

Narrow . 

High   .  . 

Narrow . 

High 

Narrow 

High... 

Narrow . 

High... 


Number  of  cases. 


Actual. 


17 
o 

8 
o 
I 
o 

3 
o 

8 

o 

12 
O 
2 
O 
O 

o 
I 
8 
o 
I 
4 

5 
o 
o 


Calcu- 
lated. 


15 
5 
5 
1.6 

5 

1.6 

1.6 

0.5 

7-3 

2.5 

2.5 

0.8 

2.5 
0.8 
0.8 
0-3 
7.3 
2.8 

2.5 
0.8 

2.5 
0.8 
0.8 
0.0 


Ijorth  Carolina  State  Library 
Raleigh 


SINGI.E-COMB   MINORCA   AND    WHITR-CRESTED   POLISH. 


17 


This  table  gives  the  distribution  of  characteristics  in  70  individuals. 
Grouping  the  individuals  under  certain  alternative  characters,  we  have  the 
following  relations  of  actual  and  calculated  frequency  of  occurrence  of  each 
characteristic  : 


Characteristic. 

Actual. 

Expected. 

Characteristic. 

Actual. 

Expected. 

Split  comb. , 

29 
22 

19 
49 
21 

35-0     1 

17-5 

17-5 

52.5 

17-5 

'  Hernia  present  .... 

Hernia  absent 

Nostril  hij^h 

Nostril  low 

16 
54 
14 
56 

17-5 
52.5 
17-5 

52.5 

Single  comb 

Papillae 

Crest  present 

Crest  absent 

The  actual  never  deviates  far  from  the  expected. 

If,  however,  we  compare  the  actual  number  of  cases  of  each  of  the  combi- 
nations with  the  calculated  the  result  is  instructive.  For  example,  in  the 
absence  of  correlation  of  characters  we  should  expect  a  high  nostril  to  be 
associated  with  a  single  comb  in  5  or  6  of  the  22  cases  ;  but  it  is  never  found  so 
associated.  In  fact  a  high  nostril  never  occurs  in  this  cross  dissociated  jrotn  a 
rudimentary  comb.  On  the  other  hand,  it  appears  that  a  low  nostril  may  be 
associated  with  a  rudimentary  comb,  but  in  unexpectedly  few  cases,  4  instead 
of  about  14.  Two  of  the  4  records  are  from  embryos  in  the  shell,  in  which 
therefore  adult  characteristics  were  not  fully  developed  and  the  other  two 
cases  are  recorded  as  one-half  high.  It  is  quite  possible  that  an  atypical 
nostril  and  absence  of  true  comb  are  always  associated  (fig.  11). 

In  order  not  to  complicate  the  table  too  much,  the  correlation  between 
crest  and  color  of  the  crest  feathers  was  omitted.  A  subsidiary  table  is  con- 
sequently given  here  : 

/. 

„      ^  .  f  Black 18 

Crestpresent j  White  and  black 23 

Crest  absent {  Whit^e  and  "black ::::  l!  ■.::■.■.;■.  i'. .       6 

56 

Whether  crest  is  present  or  absent  white  occurs  on  the  head  ;  but  it  is  more 
apt  than  not  to  occur  when  the  crest  is  present  and  less  apt  than  not  when 
the  crest  is  absent. 

CONCLUSIONS. 

In  the  cross  under  consideration  no  characteristic  is  inherited  in  strictly 
Mendelian  fashion,  for  in  no  case  is  dominance  complete.     The  nearest  ap- 
proach to  typical  Mendelian  dominance  is  exhibited,  in  the  present  cross,  only 
when  crest  is  crossed  with  no  crest.    The  new  additive  characteristic — crest — 
2 


l8  INHERITANCE    IN    POULTRY. 

is  dominant.  But  the  crest  of  the  first  generation  hj'brids  is  always  of  small 
size.  Likewise,  plain  head  is  dominant  over  cerebral  hernia,  but  some  of 
the  hybrids  have  exceptionall}'  high  frontal  prominences.  The  white  color 
of  crest  is  recessive  in  the  male  hybrids,  but  is  not  entirel}'  shut  out  from  the 
females.  The  high  nostril  is  recessive,  yet  the  presence  of  its  representative 
in  the  hybrid  gives  the  latter  abnormally  wide  nostrils.  Finally,  the  comb 
affords  us  a  case  of  an  organ  in  which  neither  parental  form  can  be  said  to 
be  dominant  without  such  an  extension  of  the  term  as  to  render  it  quite 
vague.  Ever}''  individual  shows  a  modified  comb — the  Y  or  0  shaped  comb. 
This  is  a  new  form — a  heterozygous  form — that  probably  reappears  in  the 
heterozygotes  of  each  generation. 

The  facts  of  correlation  show  that  crest  is  by  no  means  dependent  on 
cerebral  hernia.  At  the  same  time  I  doubt  if  the  absence  of  present  corre- 
lation disproves  the  hypothesis  that  the  crest  was  the  result  of  the  hernia.  It 
is  at  least  conceivable  that  a  characteristic  that  arose  as  a  response  to  the 
stimulus  of  an  abnormal  ontogenesis  should  become  hereditary  and  inde- 
pendent of  the  stimulus.  As  for  white  color  on  the  top  of  the  head,  it  is 
dissociable  from  the  crest,  for  wholly  black-crested  second  hybrids  occur. 

Series  II.— Single-comb  White  Leghorn  and  HouJan. 
STATEMENT  01'  PROBLEM. 

This  cross  was  undertaken  for  comparison  with  that  between  Minorca  and 
Polish,  and  to  test  the  inheritance  of  plumage  color,  extra  toe,  and  face 
feathering. 

THE  RACES  AS  A  WHOLE. 

The  Leghorn  (fig.  15)  is  typical  of  the  Mediterranean  class  of  poultrj^ — 
slender,  tall-legged,  close- feathered,  nervous,  and  non-broody — the  same  class 
as  that  to  which  the  Minorca  belongs.  The  white  Leghorns  came  originally 
from  northern  Italy.*  They  have  been  bred  in  America  since  1834.  The 
single-comb  variety  is  one  of  the  most  widely  bred  of  our  races  and  has  the 
reputation  of  being  the  greatest  egg-producer.  Considering  its  white 
plumage,  its  transparent  skin,  with  a  trace  of  yellow,  and  its  red  iris,  it 
comes  very  near  to  being  an  albino  race,  but  the  retina  is  pigmented. 

The  Houdan  (fig.  16)  comes  from  France.  It,  like  the  Dorking,  has 
doubtless  descended  from  the  5-toed  fowls  of  the  Romans,  described  by 
Columella,  which  they  probably  carried  to  Gaul  in  their  conquest  of  that 

*  Wright,  1902,  p.  385;  WyckoflF,  1904,  p.  788. 


^lyi 


SVnHB)RAWN 


SINGLK-COMB    WHITE    LEGHORN    AND    HOUDAN. 


19 


couutr3^     This  may  have  been  crossed  with  ' '  the  old  crested  race  of  Caux."* 
The  Houdan  may  be  regarded  as  one  of  the  fundamental  types. 


TABI.E  OF   CHARACTERISTICS. 


No. 

Characteristic. 

Single-comb  White  Leghorn . 

Houdan. 

I 
2 

3 
4 

5 
6 

General  plumage  color   .... 
Color  of  upper  mandible .... 

Nostrils    .      

Comb   

Face  feathering 

Chin  feathering 

White 

Yellow 

Narrow    

Single  (rarelv  cleft  behind. 
No.  II.) 

Plain 

Plain 

Plain 

Plain . .    

Yellow 

Four 

Black,  white-tipped. 
Light  horn. 
High. 
2-pronged  or  V. 

Whiskered. 
Bearded. 

7 
8 

9 
10 

Dorsal  head  plumage 

Dorsum  of  cranium 

Foot  color 

Number  of  toes .      .  .      

Crested. 
Domed. 
White. 
Five. 

DISCUSSION  OF  CHARACTERISTICS. 

1.  General  Plumage  Color. — In  the  Leghorn  this  is  typically  white, 
and  the  most  highly  selected  birds  are  without  trace  of  black  specks  or 
yellowish  lacing.  The  yellow  lacing  is  hard  to  get  rid  of.  The  Houdan 
color  consists  typically  of  black  feathers  occa.sioually 
tipped  with  white  (fig.  16). 

2.  Color  op  Upper  Mandible. — The  clear  yellow 
of  the  mandible  of  the  white  lyCghorn  is  part  of  the 
general  pigmentation  of  the  skin.  Much  yellow  pig- 
ment is  deposited  over  the  body.  It  shows  prominently 
in  the  tarsal  scutes.  The  Houdan  mandible  is  clear 
black. 


comb 


nostril 
of 


Fie.  B.  —  Dorsal  view  of 
beak  of  Houdan  gAcf 
showing  pail  of  clublike 
papillae,  c,  that  represent 
the  v-comb,  c.  /.,  cul- 
minal  fold. 


3.  Nostrils. — The  high  nostrils  of  the  Houdan 
(fig.  12)  are  like  those  of  the  Polish  fowl  (page  7). 

4.  Comb. — The  comb  of  the  Houdan  in  America  is 
the  so-called  V-comb.  It  differs  from  the  Polish  comb 
(page  7)  in  that  the  two  horns  arise  from  the  sides  of 
a  median  sweUing  (Fig.  B),  In  England  the  Houdan 
is  cultivated  with  a  leaf  comb  consisting  of  two  broad, 
flat  expansions  of  the  horns   arising  from  a  median 

ridge  like  "  a  butterfly  with  open  wings."  t  It  thus  resembles  the  posterior 
part  of  a  Y-comb  (fig.  8).  The  single  comb  of  the  Leghorn  is  very  large 
and  lops  in  the  female  to  the  right  or  left  side  of  the  head. 

*  Petersen,  C.  E.,  1905,  p.  961,  quoting  P.  Megnin  :  "El^vage  et  engraissement  des 
volailles." 

t  Hurst,  C.  C,  1905,  p.  132. 


20  INHERITANCE    IN    POULTRY. 

5.  Whiskers,  or  Muff. — This  is  a  bunch  of  long  feathers  growing  from 
the  sub-orbital  and  post-orbital  region  of  the  head.  This  characteristic,  of 
whose  origin  nothing  is  known,  has  been  engrafted  on  several  of  the  other 
French  breeds  :  the  Crevecoeur,  the  FaveroUe,  the  Du  Mante,  the  Cossack, 
the  Bourbourg,  etc.  The  muff  occurs  also  on  breeds  which  have  little  in 
common  with  the  French  fowl,  e.  g.,  the  Sultan  and  the  Orlaff  and  Pavaloff  of 
Russia. 

6.  Beard. — This  consists  of  a  number  of  long  feathers  growing  from  the 
middle  of  the  chin  and  upper  throat  region  (fig.  16).  There  is  a  fold  of 
skin  here  from  which  the  feathers  arise.  Such  a  beard  is  usually  associated 
wuth  the  muff.  The  fold  of  skin,  "  dewlap,"  is  found  in  some  Indian  Games 
and,  less  marked,  in  the  Dark  Brahma  male. 

7.  8.  Crest  ;  Cerebral  Hernia. — These  are  indistinguishable  from 
those  of  the  Polish  (pp.  8-10). 

9.  Foot  Color. — The  brilliant  yellow  color  of  the  tarsus  of  the  Leghorn  is 
strikingly  different  from  the  colorless  or  dirty  gray  tarsus  of  the  Houdan. 
There  must  be  a  special  yellow  pigment  in  the  skin  of  the  former  which  is 
absent  in  the  latter. 

10.  Number  of  Toes. — The  possession  of  an  extra  toe  (fig.  13)  is  an  ancient 
characteristic  of  poultry.  The  Latin  author  Columella,  speaking  of  the  fowl 
kept  by  the  Romans,  says  :  * '  Those  hens  are  reckoned  of  the  purest  breed 
which  are  5-clawed,  but  so  placed  that  no  cross-spurs  arise  from  the  legs." 
Since  the  tendency  to  extra  toes  must  have  arisen  spontaneously  once,  there 
is  always  a  possibility  that  it  has  done  so  several  times,  and  it  is  b}'  no 
means  certain,  although  probable,  that  the  extra  toe  of  the  Polish  is  genet- 
ically connected  with  that  of  the  Roman  fowl  referred  to.  The  following 
record  of  occurrence  of  extra  toes  in  poultry  is  interesting,  since  in  this  case 
no  relation  to  the  Roman  fowl  is  probable.  A  writer  *  in  Der  Zoologische 
Garten  states  that  Carl  Bock  in  his  "  Reich  des  weissen  Elefant,"  p.  267,  re- 
lates that  he,  in  a  journey  from  Tschengmai,  on  the  third  day  reached 
Muaug  Hawt,  a  way  station  on  the  road  to  Mulmen.  This  village  is  dis- 
tinguished for  its  6-toed  fowl.  Again,  the  Silky  fowl,  which  certainly  have 
little  in  common  with  the  Dorking,  have  extra  toes  (page  59) .  The  extra  toe 
is  to  be  regarded  as  a  sport  which  has  appeared  at  different  times  and  which 
is  easily  maintained  as  a  racial  characteristic.  The  question  of  the  inher- 
itance of  such  a  sport  is  always  interesting.  The  Houdan  has  typically 
only  one  extra  toe,  making  5  in  all ;  it  is  occasionally  found  wnth  6. 
Bateson  and  Saunders  (1902,  p.  98)  sometimes  got  6  toes  in  hybrids  between 
Leghorns  and  Dorkings.  The  length  of  the  extra  toe  and  the  completeness 
of  bifurcation  are  very  variable. 

*Laiigkavel,  B.  18S6,  p.  35. 


SINGLE- COMB    WHITE    LEGHORN    AND    HOUDAN.  21 

PREVIOUS  INVESTIGATIONS. 

During  the  progress  of  my  experiments  appeared  the  second  report  to 
the  Evolution  Committee  of  the  Royal  Society  by  Bateson  and  others. 
This  contains  a  paper  by  Hurst  (1905,  p.  133)  giving  his  results  with  White 
lyCghorn  male  X  Houdan  female.  These  will  be  considered  in  comparison 
with  my  results, 

MATERIAIv. 

The  mothers  were  two  Houdan  hens*  (fig.  16)  purchased  from  a  dealer 
as  pure  stock.  They  agreed  well  with  the  standard  requirements.  When 
bred  with  a  Houdan  male  they  produced  only  typical  Houdans. 

Tho.  father  was  a  Single-comb  White  Leghorn  f  likewise  of  unknown 
ancestry.  The  plumage  of  No.  13A  is  devoid  of  black  pigment,  and  mated 
with  White  L,egliorn  hens  it  has  produced  only  White  lyCghoru  offspring. 

RESULTS. 

I.  General  Plumage  Color. — First  hybrid  generation.  Of  41  individuals 
all  were  white  in  plumage  (fig.  17),  but  almost  without  exception  both  in 
down  plumage  and  that  of  the  adult  there  were  traces  of  black  on  one  or 
more  feathers,  particularly  those  of  the  back  ;  more  especially  was  this  true 
of  the  females  than  of  the  males. 

Hurst  (1905,  p.  133)  got  II  black  chicks  out  of  105  offspring  and  in  the 
first  plumage  these  developed  into  6  black  (all  pullets)  and  5  barred  (all 
cockerels).  Here  also  females  have  more  pigment  than  males.  Of  the  white 
chicks  all  except  two  developed  black  ticking.  Doubtless  these  two  were 
males. 

Second  hybrid  goie ration.  When  these  hybrids  were  crossed  inter  se,  out  of 
50  individuals  9  were  markedly  pigmented  like  the  Houdan.  This  is  18  per 
cent  of  all  cases,  expectation  being  25  per  cent.  With  larger  numbers 
Hurst  (1905,  p.  138)  got  24.3  per  cent  black.  Equall)'  striking  is  the 
occurrence  of  many  pure  white  individuals  along  with  the  impure  whites. 
The  pure  whites  that  were  reared  to  maturity  proved  to  be  males ;  the  impure 
whites  were  females. 

First  hybrid  ( No.  Sy  $)  crossed  ivith  white  Leghorn  {No.  /z  9  ).  The  father 
was  pure  white  ;  the  mother  was  speckled  with  black.  Of  22  offspring  all  were 
white,  but  some  had  single  pigmented  feathers.  All  males  (9)  are  pure  white, 
excepting  No.  562,  which  has  some  black  on  two  feathers  of  the  left  wing 
coverts,  and  No.  649,  which  has  one-half  of  one  right  wing  covert  black. 
My  only  certain  female  has  a  score  of  partly  black  feathers.  Hurst  (1905, 
p.  139)  obtained  66  clear  white  chicks  and  69  white,  ticked  with  black.     I 

*Nos.  8  aud  11,  received  July  i,  1904,  from  Geo.  C.  Ely. 
t  No.  13A.,  received  Sept.  15,  1904,  from  a  farmer. 


22 


INHERITANCE    IN    POULTRY 


judge  this  equality  to  indicate  a  difference  of  color  in  sex  ;  or  else  the  pig- 
mented individuals  are  heterozygotes.  Possibly  the  females  are  the  hetero- 
zygous forms — the  males  homozygous. 

2.  Color  of  Upper  Mandible. — This  assumes  its  final  condition  so  late  in 
life  that  definite  statistics  will  not  be  given  now. 

First  hybrid  generation.  A  few  young  are  recorded  as  showing  yellow. 
The  rest  are  white  ;  this  is  probably  the  young  condition  of  the  light  horn 
of  the  adult  Houdan.     Light  horn  seems  dominant. 

Second  hybrid  generation.  A  few  cases  of  black  mandible  are  recorded, 
even  in  the  young,  where  pigment  is  less  developed. 

First  hybrid  {8y)  crossed  with  white  Leghorn.  All  older  chicks  have  white 
mandibles  ;  there  are  no  blacks. 

3.  Nostrils. — First  hybrid generatioti.  Of  25  individuals,  all  but  one  have  a 
nostril  of  one-half  width  or  less — thus  approaching  the  white  Leghorn  type. 
The  exceptional  individual  (No.  386  ?  )  has  a  typical  high  nostril  and  is 
peculiar  in  respect  to  comb  also.  Only  one  individual  is  recorded  as  having 
as  narrow  a  nostril  as  the  Minorca. 

Seco7id  hybrid  generation.    Forty-nine  individuals  give  : 


Characteristic. 

Frequency. 

Per  cent. 

Narrow  (24)  and  intermediate  (8)     

32 

^7 

65.5 

34-5 

High 

Total   

49 

loo.o 

On  the  assumption  that  "  narrow  and  intermediate  "  includes  pure-narrow 
and  heterozygous  individuals,  while  "high"  includes  recessive,  pure-high 
individuals,  we  should  expect  75  per  cent  and  25  per  cent  in  the  two  classes 
respectively — only  an  approximate  agreement  with  the  actual. 

First  hybrid  {No.  87$)  crossed  with  white  Leghorn  (71^).  The  father 
has  a  "one-fourth"  nostril;  the  mother,  of  course,  a  typical  "narrow" 
one.  Of  24  individuals  12  are  recorded  as  narrow  ;  12  as  intermediate  of 
some  grade.  This  gives  the  ratio  1:1,  which  we  expect,  assuming  the  inter- 
mediate nostril  to  be  the  heterozygous  type  ;  the  narrow,  the  pure  type. 

4.  Comb. — Fii^st  hybrid  generation.  Of  41  individuals  40  have  the  Y-shaped 
comb  in  some  form  (fig.  17).  This  comb  resembles  that  of  the  Minorca 
X  Polish  hybrid.  There  is  no  case  of  a  single  comb  in  this  generation,  but 
there  are  two  cases  in  which  the  posterior  end  of  the  comb  is  merely  much 
thickened.  On  the  whole  the  present  series  of  cleft  combs  differs  from  the 
former  in  that  a  smaller  proportion  of  the  comb  is  split — no  cases  of  wholly 
split  or  cup  combs  occur,  although  in  one  important  case  (87  ^  )  two-thirds 


SINGLE-COMB   WHITE   LEGHORN   AND   HOUDAN. 


23 


of  the  comb  is  cleft.  A  new  characteristic  of  this  series  of  cleft  combs  is 
the  occasional  appearance  of  a  median  comb  lying  between  the  two  wings  of 
the  cleft  comb — a  posteriad  continuation  of  the  single  part  of  the  comb. 
This  condition  appears  in  three  cases  (258  $  ,  259  ^  ,  448  ^  ).  It  is  important 
for  the  interpretation  of  the  cleft  comb.  It  gives  the  posterior  part  of  the 
hybrid  comb  the  triple  condition  characteristic  of  English  Houdans, 

The  one  case  that  lacks  the  Y-shaped  comb  is  No.  386  9  (with  high 
nostrils).  She  has  only  a  pair  of  papillae.  Hurst  (1905,  p.  133)  got  no 
single  comb  in  105  offspring. 

Second  hybrid  generation.  Fifty-five  individuals  show  the  following  dis- 
tribution of  comb  forms  : 


Characteristic. 

Frequency. 

Per  cent. 

Actual. 

Expected. 

Single 

Y  comb  ....      

0  0    or  absent 

Total 

17 
23 
15 

30.9 
41.8 

27.3 

a             /s 

25      (18.75) 
50      (56.25) 
25      (25.00) 

55 

loo.o 

100    (100.00) 

The  Y  comb  being  the  heterozygous  form  should  appear  in  50  per  cent  of 
the  cases  ;  each  of  the  other  forms  in  25  per  cent.  The  deviation  from 
expectation  is  of  the  same  character  as  in  Series  I.  That  the  approximation 
to  theory  is  less  close  is  probably  due  to  the  smaller  total  number.  Hurst 
(1905,  p.  138)  obtained  56  ordinary  single  combs  in  226,  or  24.8  per  cent. 

First  hybrid  {8y  $  )  crossed  with  white  Leghorn  (/z  $  ).  The  Y-shaped  comb 
crossed  with  single  gives,  in  26  individuals  : 


Characteristic. 

/. 

Per  cent. 

Single 

15 
II 

26 

57-7 
42.3 

Cleft,  etc.  {^see  Remarks) 

Total 

lOO.O 

Remarks:  Including  two  cases  in  which  a  median  ridge  runs  through 
the  cleft  comb.  Of  these  one  is  a  nearly  typical  pea  comb  except  that 
the  side  lobes  are  higher  than  the  median  one.  Including,  furthermore, 
one  case  of  an  arrow-shaped  comb,  two  parallel  V  's  occurring  in  front 
and  behind,  respectively,  being  joined  by  a  median  ridge.  Including, 
finally,  two  cases  of  cup-comb. 

Here  the  expected  equality  is  approached.  Hurst  (1905,  p.  139)  obtained 
60  ordinary  single  combs  in  135  individuals  of  this  cross,  or  44.4  per  cent. 

5,  Face  Feathering. — First  hybrid ge?ieration.  Of  24  recorded  cases  all 
show  the  muff  (fig.  17). 


24 


INHERITANCE    IN   POULTRY. 


Second  hybrid  generation.  All  individuals  (26)  whose  face  feathering  was 
observed  are  recorded  as  muffed;  concerning  a  greater  number  (35)  the 
record  is  silent.  What  has  become  of  the  expected  25  per  cent  of  muffless 
individuals?  It  is  possible,  but  on  strict  chance  hardly  probable,  that  the 
uiufBess  individuals  all  died  young.  A  decisive  answer  to  our  question 
must  await  further  experimentation. 

First  hybrid  {Sy  $ )  crossed  i^'ith  white  Leghorn  (7/  9  )•  Only  one  parent  is 
muffed.  Muffed  and  non-muffed  offspring  occur  in  approximate  equality  ; 
but  even  in  the  adult  muffing  is  not  full  in  amount.  This  cross  confirms  the 
result  of  the  first  that  muffing  is  dominant,  but  it  is  not  perfectly  so. 

6.  Beard. — In  \^i&  first  hybrid  generation  all  individuals  are  bearded.  When 
these  hybrids  are  crossed  with  the  white  I,eghorn  about  half  of  the  offspring 
are  beardless.     Beard  is  dominant. 

7.  Cerebrai,  Hernia. — \\xt\i&  first  hybrid  generation  all  (24)  individuals 
were  without  external  evidence  of  the  cerebral  hernia.  In  the  second  hybrid 
generation  out  of  45  individuals  11  had  the  hernia  (fig.  14)  and  34  had 
none,  or  24.4  per  cent  and  75.6  per  cent  respectively.  When  the  hybrid 
zvas  crossed  zcith  the  white  Leghorn  (71$)  no  individual  with  the  hernia 
appeared.  The  cerebral  hernia  is  a  recessive  characteristic.  However,  the 
height  of  the  frontal  dome  is  variable,  even  in  the  pure-bred  Houdans,  and 
on  at  least  one  occasion  the  cerebral  prominence  in  an  unhatched  h5-brid 
was  so  high  that  it  was  doubtful  whether  or  not  it  might  represent  a  hernia. 
Here,  as  in  Series  I,  plain-headedness,  though  clearly  dominant,  is  imper- 
fectly so. 

8.  Crest. — First  hybrid geyieration.  Of  25  individuals  all  are  crested.  Hurst 
(1905,  p.  134)  gets  the  same  result.  Second  hybrid  generatioii.  Of  19  indi- 
viduals 6  are  non-crested,  or  31.6  per  cent,  approaching  the  expected  25  per 
cent.  The  remainder  are  crested.  First  hybrid  {8j  $ )  crossed  with  white 
Leghorn  (7/9)-  Of  15  individuals  6,  or  40  per  cent,  are  without  crest. 
Expectation  is  50  per  cent.  Crest  is  clearly  dominant,  yet  in  the  first  hybrid 
it  is  never  so  large  as  in  the  Houdan.  This  fact  is,  I  take  it,  due  to  imperfect 
dominance.  It  may,  however,  be  associated  physiologically  with  the  absence 
of  a  cerebral  hernia. 

9.  Foot  Color. — In  the  first  hybrid  generation  this  always  becomes  white  in 
the  adult,  although  sometimes  yellow  in  young  birds.  In  the  second  genera- 
tion of  hybrids  bred  inter  se  or  with  the  White  L,eghorn  stock,  yellow  reappears 
as  leg  color.  Statistics  would  be  misleading  on  this  point,  as  permanent  leg 
color  is  reached  only  on  maturity.  It  may  be  concluded  that  white  is  domi- 
nant over  yellow. 


SINGI.E-COMB    WHITE    LEGHORN   AND    HOUDAN. 


25 


10.  Number  op  Toes. — First  hybrid  generation .  Among  37  individuals  the 
following  distribution  appears  : 


Number  of  toes. 

/. 

Per  cent. 

4-4 

4-5 

s-s 

IV 

16.2 

83.8 

Total 

37 

lOO.O 

Hurst  (190.5,  p.  133)  got  among  105  birds  103  with  trace  of  extra  toe 
(including  duplication  of  nail  and  hyperphalangia)  and  two  without  any  such 
trace.  The  difference  in  the  proportions  of  extra  and  normal  toes  between 
Hurst's  and  my  results  is  partly  a  matter  of  classification  and  perhaps  partly 
due  to  the  real  difference  in  potency  of  the  extra-toe  characteristic  in  the 
two  strains. 

Second  hybrid  generation.  To  learn  if  the  individuals  with  4-4  toes  were 
merely  imperfect  dominants  or  true  recessives  I  mated  two  of  them  (Nos, 
84  9  and  869)  with  their  brother,  a  4-toed  cock  (No.  83  <?  ) .  Of  23  offspring, 
17  were  normal-toed  and  6  had  extra  toes  on  one  or  both  feet,  or  nearly  25 
per  cent  with  extra  toes.  Expectation,  on  the  other  hand,  was  either  (a) 
if  the  4-4-toed  were  recessives  there  should  be  no  extra  toes,  or  else  {b)  if 
extra  toe  here  merely  fails  to  dominate  there  should  be  75  per  cent  with 
extra  toes.  Hurst  (1905,  p.  150)  mated  together  two  4-4-toed  hybrids  and 
got  14  extra- toed  to  8  normal,  or  63.6  per  cent  extra-toed.  He  also  mated 
the  same  4-4  hybrid  cock  with  a  4-toed  Hamburg  Cochin  hen,  and  about 
half  the  offspring  had  extra  toes.  He  concludes  :  "  These  results  prove  that 
the  apparently  recessive  feet  with  no  trace  of  extra  toe  ....  are  in  reality 
DR's,  as  both  birds  gave  chicks  with  e.  t.  when  bred  together  and  with  pure 
recessives. ' '  I  am  inclined  to  doubt  if  this  is  the  whole  story,  for  one  of  my 
two  4-4-toed  hybrid  hens,  namely.  No.  86,  mated  with  83  $  ,  gave  12  offspring 
with  4-4  toes  and  no  certain  offspring  without  normal  toes.  This  looks  as 
though  86  9  and  83  ^  were  both  truly  recessive.  No.  84  9  ,  on  the  other 
hand,  produces  extra-toed  and  normal-toed  individuals  in  about  equal  pro- 
portions.    Further  experiments  with  83,  84,  and  86  are  planned  for  1906. 

Second  hybrid  {8j$)  niated  zvith  white  Leghorn  (7/9  )•  The  father  (87) 
has  an  extra  toe  on  the  left  side  only.  Of  25  offspring  17  have  4  toes 
on  each  side,  6  have  5  toes  on  each  side,  and  2  have  an  extra  toe  on  one 
side  only. 

II.  Correlation  of  Characters. — The  first  hybrids  between  white 
Leghorns  and  Houdans  show  a  fairly  constant  association  of  characteristics, 
a  white  plumage  flecked  with  black,  white  mandible,  uarrovvish  nostrils, 
Y-shaped  comb,  muffed  and  bearded  face,  reduced  crest  on  a  domeless  head. 


26 


INHERITANCE   IN   POULTRY. 


white  leg:s,  and  toes  that  are  usually  but  not  always  meristically  abnormal. 
When  the  hybrids  are  bred  inter  se  we  get  varied  combinations  of  char- 
acteristics, as  follows  (D  meaning  dominant  and  R,  recessive) : 


Comb. 

NostriL 

Hernia. 

Toes. 

Plumage. 

Actual  No. 
of  cases. 

f 

Low  (D)  

Low 

Low 

Low 

Low 

High 

High 

High 

High 

Low 

Absent  (D) . . 
Absent   .... 

Absent 

Present  

Present  

Absent 

Absent  

Absent  

Present  

Normal  (R) 
Normal.  . . . 

Extra 

Normal. . . . 

White  (D) 

6 

Black  and  white 

White 

I 

3 
o 

Y 

Extra 

Normal .... 
Normal .... 
Extra 

I 

White 

I 

Black  and  white. .    . 

I 
o 

o 

- 

Absent 

Absent  .  .    , . 

Absent 

Absent 

Present  

Present  

Absent 

Absent 

Present  

Present 

Absent 

Absent 

Absent   

Present  

Present  

Absent 

Absent 

Absent 

Absent 

Present  

Present  .... 
Present  

Normal .... 
Normal .... 

Extra 

Extra 

Normal. . . . 

White 

6 

Low 

Low 

Low 

1/OW 

Low 

High 

High 

High 

High 

Low 

Low 

Black  and  white 

White 

Black  and  white  .... 

o 

3 
o 

*2 

1 

Extra 

o 

Normal .... 

o 

Extra 

o 

Normal .... 
Extra 

":''':''y''.':''...\. 

o 
o 

c 

Normal .  .  . 
Normal ... 

Extra 

Normal .... 

White 

o 

Black  and  white 

o 

Low  

o 

Low 

Low 

High 

I 

Extra 

o 

Normal .... 
Normal .... 

Extra 

Extra 

Normal .... 
Normal.  . . . 
Extra 

White 

4 

High 

Black  and  white 

White 

Black  and  white 

White 

Black  and  white 

I 

High 

High 

High 

3 

I 

X 

High 

I 

High 

o 

^ 

.... 

38 

*Fig.  14. 
CONCLUvSIONS. 

In  the  series  of  crosses  between  the  White  Leghorn  and  Houdan,  Mendtlian 
results  were  obtained  as  in  the  first  series.  Dominance,  however,  is  frequently 
imperfect.  The  plumage  color  of  the  offspring  of  a  pure  homogametous  white- 
and-black  and  a  white  are  rarely  pure  white.  Likewise  in  the  second  hybrid 
generation  impure  whites  occur.  Also,  nostril-height  exhibits  imperfect 
dominance  of  the  narrow  type.  The  muff,  beard,  and  crest,  though  always 
present  in  the  first  hybrid  generation,  are  apparent!}'  alwaN's  reduced.  The 
cerebral  hernia,  though  recessive,  affects  the  dominant  normal  skull. 

A  heterozygous  for/n  results  from  hybridizing  the  single  and  V-shaped  comb. 
The  cleft  comb  is  a  neomorph,  of  which  more  will  be  said  in  the  sequel 
(page  65). 

Polydactylisra  does  not  readily  fall  into  the  Mendelian  formula.  Hurst's 
results,  although  suggestive,  need  support  from  other  experiments. 


HOUDAN    AND    SINGLE- COMB    BLACK    MINORCA. 


27 


Few  characters  are  correlated  ;  the  second  hybrid  generation  exhibits  all 
combinations,  except  that  high  nostril  and  single  comb  do  not  occur  together 
here  any  more  than  they  do  in  the  Minorca-Polish  hybrids. 

Among  heterozygous  individuals,  with  Y-shaped  comb,  the  combination 
of  dominant  characteristics  (narrow  nostril,  no  hernia,  and  white  plumage) 
is  the  commonest,  forming  nine-thirteenths  of  all.  These  are  also,  apart 
from  the  Y-comb,  all  Leghorn  characteristics.  It  appears,  too,  with  the  given 
parentage,  that  normal  toes  are  usually  present.  The  low  nostril  and  cerebral 
hernia  combination  occurs  several  times  with  or  without  extra  toe.  The 
combination  refutes  the  notion  of  Wright  (quoted  at  page  8)  that  there  is  any 
necessary  relation  between  cerebral  hernia  and  "cavernous"  nostril.  A 
high  nostril  was  in  two  instances  (both  of  which  died  very  young,  one  before 
hatching)  associated  with  a  Y-comb,  but  it  is  doubtful  if  the  median  portion 
would  have  developed. 

The  single  comb  may  occur  associated  with  a  hernia  {e.g.,  No.  443, 
fig.  14),  with  extra  toes  and  with  mottled  plumage,  but  in  my  records  so 
far  it  is  never  associated  with  a  high  nostril. 

The  V-shaped  comb  is  commonly  associated  with  high  nostril,  but  rarely 
with  a  low  one,  despite  the  fact  that  low  nostril  is  dominant.  It  occurs  on 
white  individuals  thrice  as  frequently  as  on  black-and-white  ones ;  it  shows 
no  preference  for  the  extra  toe. 

The  hernia  is  never  found  dissociated  from  the  crest ;  but  the  crest  occurs 
three  times  as  often  as  the  hernia. 

Series  III.— Houdan  and  Single-comb  Black  Minorca, 

STATEMENT  OF  PROBLEM. 

This  series  was  undertaken  to  compare  the  behavior  of  the  Houdan  with 
that  of  the  Polish  (Series  I,  page  6)  when  crossed  with  the  Minorca. 

THE  RACES  AS  A  WHOLE. 

The  Houdan  is  described  at  page  18  and  the  Black  Minorca  at  page  6. 
Both  of  the  races  are  fundamental  and  old.  The  Houdan  contains  the 
larger  assemblage  of  new  characteristics. 

Table  of  characteristics. 


Characteristic. 

Houdau. 

Discussed 
at  page — 

Single-comb  Black 
Minorca. 

Discussed 
at  page — 

I.  General  plumage  color. . 
0    Comb  form 

Black  and  white. . 

V 

Wide  

Present ....    

Present 

Present 

Present 

White 

19 
19 
19 
20 

20 

19 
20 

20 

20 

Black 

1 

Narrow 

Absent 

29 

7 

3.  Nostril  form 

4.  Crest 

5.  Cerebral  hernia 

6.  Muff 

7.  Beard 

8.  Foot  color 

9.  Toes 

7 

Absent 

Absent    

Absent    

Black 

4-4 

29 

5-5   

28  INHERITANCE    IN    POULTRY. 

MATERIAL. 

As  mothers,  Nos.  8  and  1 1  (page  21),  original  Houdan  stock,  and  later  their 
daughters,  Nos.  60  and  81,  were  used.  No  trap  nests  were  employed  in 
this  series  and  consequently  mothers  are  not  exactly  known. 

FatJicr:  No.  27,  bred  at  the  station,  August,  1904,  son  of  No.  12, 
Minorca  cock  (page  6)  and  a  Minorca  hen. 

RESULTS. 

1 .  General  Plumage  Color. — The  young  hybrids,  like  the  j'-oung  black 
Minorcas,  contain  much  white  on  the  bell}''  and  primaries.  In  later  molt- 
ings  the  white  is  replaced  by  black,  but  even  at  five  months  the  primaries 
are  sometimes  mealy  or  white-spangled.  Except  for  this  the  hybrids  have 
lost  the  Houdan  white  and  are  of  the  Minorca  color.  Minorca  uniform 
black  is  dominant  over  the  Houdan  mottling. 

2.  Comb. — First  hybrid  gC7ieration.  Of  20  offspring  18  have  a  Y-shaped  comb 
like  the  hybrids  of  Polish  and  Minorcas.  In  two  cases  (of  egg  embryos)  the 
comb  was  recorded  as  single,  but  this  is  probably  only  the  limiting  condi- 
tion of  the  Y-shaped  comb,  which  is  here  also  the  heterozygous  form. 

3.  Nostril  Form. — First  hybrid  generation.  In  no  case  does  the  nostril 
width  exceed  one-half.  As  in  Series  I  and  II,  there  is  imperfect  dominance 
of  the  narrow  form.  However,  the  nostril  in  this  cross  runs  lower  than  in 
the  Leghorn  X  Houdan  cross. 

4.  Crest. — This  is  present  in  all  first  hybrids  reared  to  a  sufficient  age  to 
render  an  opinion  possible, 

5.  Cerebral  Hernia. — Fj.  Always  absent.  One  egg  embryo,  which  died 
at  about  17  days  of  incubation,  had  a  vesicle  protruding,  uncovered  by 
skin,  from  the  top  of  the  head  at  the  usual  position  of  the  hernia.  Such  a 
teretological  case  is  not  uncommon  in  straight- bred  Houdans.  It  is  note- 
worthy to  find  it  here  where  the  cerebral  hernia  is  recessive. 

6.  7.   Muff  and  Beard. — F,.  Present  in  all  older  hybrids. 

8.  Foot  Color. — Fj.  Always  black  as  in  the  Minorca. 

9.  Toes. — Of  21  hybrids,  12  have  5-5  toes,  3  have  5-4  toes,  and  6  have  4-4 
toes.  The  proportion  without  extra  toes  is  higher  than  in  the  lyCghoru  x 
Houdan  first  cross,  being  there  16.2  per  cent,  here  28.6  per  cent. 

CONCLUSIONS. 

The  following  characteristics  apparently  exhibit  alternative  inheritance: 
Plumage  color,  nostril  form,  crest,  cerebral  hernia,  muff  and  beard,  leg 
color,  and  number  of  toes.  Dominant  are:  Uniform  black  plumage  color 
(imperfect),  narrow  nostril  (imperfect),  crest  (imperfect),  cerebral  hernia 
(imperfect),  muff  and  beard  (imperfect),  and  black  leg  color.  Of  these  the 
crest,  muffling,  and  black  leg  color  are  positive  characters  in  de  Vries'  sense 
and  are  dominant.     The  color  pattern  of  the  Houdan  yields  here  to  black 


SINGI.ECOMB   LEGHORN   AND   ROSE-COMB   MINORCA. 


29 


as  it  does  in  Series  II  to  white  ;  mottling  is  recessive  to  solid  color.  The 
comb,  crest,  muffling,  and  extra  toe  are  inherited  essentially  as  in  Series  II. 
Striking  is  the  nearly  universal  imperfection  of  dominance. 

Series  IV.— Single-comb  White  Leghorn  and  Rose-comb  Blaci<  Minorca. 
STATEMENT  OF  PROBIvEM. 

This  cross  was  undertaken  to  learn  the  inheritance  in  these  races  of  the 
characteristics  described  below. 

THE  RACES  AS  A  WHOLE. 

The  I,eghorn  has  been  described  at  page  18  ;  the  Minorca  at  page  6. 

TABLE  OF   CHARACTERISTICS. 


No. 

Characteristic. 

Single-comb      ;  Discussed 
White  Leghorn,     at  page — 

Rose-comb 
Black  Minorca. 

Discussed 
at  page — 

I 

General  plumage  color. . 

Comb  form 

Foot  color 

White 19 

Single 19 

Yellow 20 

Black 

29 
29 
29 

2 
3 

Rose . . 

Blue-black. .  . . 

REMARKS  ON  THE  CHARACTERISTICS. 

1.  General  Plumage  Color. — Black  is  one  of  the  constituents  of  the 
color  of  Gallus  bankiva,  being  the  chief  color  of  the  breast.  Just  how  a 
wholly  black  condition  of  plumage  was  attained  is  of  course  not  exactly 
known  ;  there  are,  however,  manj^  instances  known  of  melanic  sports  among 
birds.  It  is  probable  that  wholly  black  varieties  have  arisen  as  a  result  of 
excessive  production  of  the  black  pigment,  melanin. 

2.  Comb  Form. — The  rose  comb  is  a  broad  mass  of  erectile  tissue  replacing 
the  single  comb.  Anteriorly  it  overhangs  the  nostrils  and  extends  over  and 
back  of  the  eyes.  The  upper  surface  is  covered  by  numerous  tubercles. 
These  do  not,  in  5'oung  birds  and  females,  run  wholly  at  random  but  tend  to 
lie  in  five  or  more  parallel  lines.  Posteriorly  the  rose  comb  ends  in  a  finger- 
like process  or  spike.  The  rose  comb  is  the  last  term  of  the  series  starting 
at  the  single  comb  and  having  the  triple  or  pea  comb  for  its  middle  term. 

3.  Foot  Color. — The  den.se  black  color  of  the  scutes  of  the  foot  of  the 
Minorca  constitutes  a  positive  or  additive  characteristic  as  contrasted  with 
the  pigmentless  condition  of  the  yellow- footed  White  Leghorn. 

MATERIAL. 

As  mothers  three  White  Leghorns  were  used,  of  unknown  ancestry  but 
reputed  pure.  They  had  fair  Leghorn  points  except  as  noted  in  the  descrip- 
tions given  below.  When  mated  with  White  Leghorn  I3A(?  they  produced 
only  white  offspring. 

lOA.   Feathers  all  white  ;  comb  strictly  single. 


30  INHERITANCE    IN    POULTRY. 

II A.  Feathers  mostly  white,  but  some  are  sooty.  The  single  comb  is 
cleft  behind  for  about  one- fourth  of  its  total  length. 

I2A.   Feathers  all  white  ;  comb  strictly  .single. 

The  father,  No.  9A,  also  of  unknown  parentage,  has  a  large  ro.se  comb 
90  mm.  long  by  44  mm.  broad  at  its  widest  part.  The  tubercles  are  very 
irregular,  but  five  rows  of  them  can  be  discerned.  The  plumage  is  prevail- 
ingly black,  but  many  feathers  of  the  back  are  tipped  with  white  and  several 
primaries  are  almost  or  quite  white. 

RESULTS. 

This  series  of  experiments  has  been  carried  as  yet  through  only  the  first 
hybrid  generation. 

1 .  Plumage  Color. — Eighty-three  fir.st  hybrids  were  obtained  of  which  74 
were  white,  either  pure  or  with  some  black  feathers,  and  9  were  deeply  pig- 
mented. Females  A  and  C  yielded  only  white  offspring.  Female  B,  on  the 
other  hand,  produced  chiefly  dark  birds,  recorded  as  "blue"  or  "black- 
and-white."  She  was  the  mother  of  the  9  pigmented  birds  just  mentioned. 
B's  germ  cells  are  probably  mixed.  The  only  two  of  B's  offspring  reared 
to  maturity  are  blue  like  the  so-called  "Andalusian  breed"  (fig.  54,  pi.  xvii). 
Now  blue  is  a  combination  of  black  and  white  and  is  a  "  heterozygous  form." 
If  blue  birds,  one  of  which  is  male,  the  other  female,  breed  together,  both 
pure  black  and  impure  white,  as  well  as  blues  agaiu,  are  to  be  expected  in 
the  proportions  of  1:1:2  respectively.--'  Of  the  white  offspring  of  both  A 
and  C  it  is  noteworthy  that  the  males  are  mostly  pure  white  (/.  e. ,  without 
trace  of  black,  although  often  suffu.sed  with  yellow),  while  the  females  are 
always  .specked  with  black. 

2.  Comb  Form. — Of  80  first  hybrids  40  have  single  comb  and  40  rose  comb. 
This  result  indicates  first  that  the  cock  is  a  heterozygote  and  consequently 
produces  in  its  germ  glands  two  kinds  of  germ  cells,  viz,  those  with  the  .single- 
comb  and  those  with  the  rose-comb  determinants  and  second,  that  rose  comb 
is  dominant.  Then  :  R  single  X  DR  rose  gives  50  per  cent  DR  rose  and  50 
per  cent  RR  single. 

Bateson  and.  Saunders  (1902,  pp.  102,  103)  find  rose  comb  of  Wyandotte 
or  White  Dorking  dominant  over  single  comb  of  the  L,eghorn.  Hurst 
( 1905.  P-  134)  crossed  a  White  IvCghorn  with  a  Black  Hamburgh  (rose  comb) 


*Tegetmeier  (1867,  p.  185)  states  that  blue  Polish  bred  together  throw  cuckoo,  white  or 
speckled  produce.  Wright  (1902,  pp.  399-401)  states  that  "Andalusians  "  constantly  throw 
black  and  also  white  chicks.  Blue  chicks  are  frequently  produced  by  crossing  black  and 
white.  Wright  (1902)  mentions  such  a  result  from  crossing  black  and  white  Langshans 
(p.  291)  and  Wyandottes  (p.  318).  Such  blues  also  throw  whites  and  blacks.  Inher- 
itance of  blue  is  discussed  by  Bateson  and  Saunders  (1902,  pp.  131-132)  and  by  Bateson 
and  Punnett  (1905,  pp.  118 -119).  In  the  latter  paper  it  is  stated  that  of  75  offspring  of 
Andalusians  17  were  "  white  splashed,  36  blues,  22  blacks."  A  blue  bred  to  awhile  pro- 
daced  34  blue  and  20  white  splashed ;  bred  to  a  black  it  gave  27  blue  and  19  black. 


SINGLE- COMB    MINORCA    AND    DARK    BRAHMA.  11 

aud  got  rose  combs  in  all  of  the  offspring.  Here,  too,  rose  comb  is  domi- 
nant over  single  comb. 

Rose  comb  is  a  positive  variation.  It  behaves  in  Meudelian  fashion. 
Although  a  neomorph,  it  is  dominant. 

3.  Foot  Color.— Excluding  from  consideration  all  but  the  older  hybrids, 
40  showed  foot  coloring  as  follows  : 

Black,  bluish,  willow,  or  greeu q 

•  White '..'.'.'.'.'..       7 

Yellow "  ' 24 

Total ^ 

This  result  indicates  that  one  of  the  parents  (probably  the  male)  is  a 
heteroz5^gote  containing  traces  of  some  white-legged  ancestor.  Yellow 
appears  to  be  dominant  over  white  and  black,  but  to  be  imperfectly  so.  The 
black  X  yellow  gives  greeu  or  willow;  the  whitened  5^ellow  is  "white." 
Hurst  (1905,  p.  137)  finds  that  when  blue-footed  and  yellow  footed  individ- 
uals are  crossed,  the  offspring  have  light-blue  feet.  Yellow  is  in  his  case 
recessive. 

CONCLUSIONS. 

In  general,  plumage  color,  foot  color,  and  comb  form  are  inherited  in 
Meudelian  fashion.  White  plumage  is  dominant,  although  imperfectly  so  ; 
wherefore  we  have  spotted  whites  and  even  blues.  Rose  comb  is  dominant  ; 
whether  perfectly  so  can  not  be  determined  until  later.  Yellow  foot  color 
seems  to  be  dominant,  but  is  imperfectly  so,  even  the  yellow  legs  showing 
traces  of  black. 

Series V. — Single-comb  Black  Minorca  and  Dark  Brahmaf 

STATEMENT  OF  PROBI.EM, 

This  cross  was  made  to  see  the  result  of  uniting  two  races  as  unlike  as 
possible  in  origin  and  general  form. 

THE  RACES  AS  A  WHOLE. 

The  Minorcas  have  been  already  described  at  page  6.  The  Dark  Brahma 
race  was  originally  imported  from  India  near  the  home  of  Galhis  bankiva  ; 
yet  it  differs  from  it  as  much  as  does  the  Minorca.  It  is  a  blocky,  short, 
stout-legged  bird,  is  fluffy  in  plumage,  and  has  a  small  pea  comb  and  small 
wattles.  It  is,  moreover,  sexuall}^  dimorphic.  The  male  (fig.  19,  pi.  v) 
has  much  more  black  in  its  plumage  and  is  very  differently  marked  from 
the  penciled  or  barred  female  (fig.  18).  The  Dark  Brahma  has  so  many 
characters  unlike  those  of  the  Jungle  fowl  that  it  is  now  thought  to  be 
chiefly  derived  from  a  different  ancestor,  namely,  that  of  the  Aseel  and 
Indian  races. 


32 


INHERITANCK    IN    POULTRY. 


TABLE   OK  CHARACTERISTICS. 


No. 


2 

3 
4 
5 
6 

7 
8 

9 


Characteristic. 


General  color. 


Single-comb 
Black   Rlinorca. 


Black  in  both  sexes. 


Foot  feathering. 
Vulture  hock. . 


Absent 
Absent 


Wing  coverts ,  Black 


Wing  coverts  (wing  bar) Black 

Comb Single 

Earlobe  color White,  red  mottling. 

Iris  color |  Brown 

Foot  and  beak  color Blue-black 


Dark  Brahma. 


Complex  black,  red  and 
white  pattern  ;  sexes 
dissimilar. 

Black,  white,  and  red. 

Pea. 

Red. 

Yellow. 

Yellow. 

Present  and  heavy. 

Present. 

Black,  white,  and  red. 


REMARKS  ON  THE  CHARACTERISTICS. 

1 .  General  Plumage  Color. — Tha  adult  Minorca  has  a  completely  glossy 
black  plumage.  In  the  chick  of  two  weeks  the  whole  ventral  surface  is 
covered  with  a  white  down,  and  certain  of  the  primaries,  especially  those  at 
the  distal  end  of  the  series,  are  partly  or  wholly  white.  The  coverts  over- 
lying these  reminges  are  usually  white  also.  The  white  on  the  wing  grad- 
ually disappears  in  successive  molts. 

The  adult  Dark  Brahma  has  a  sexual  dimorphism  of  color.  The  female 
(fig.  1 8)  is  nearly  uniformly  peticilei  black  and  straw  color.  The  hackles 
have  a  broad  whitish  margin  and  the  inner  half  of  the  vane  is  solid  black. 
The  male  (fig.  19)  has  solid  glossy  greenish-black  feathers  in  the  tail,  white 
feathers  on  top  of  the  head,  in  the  middle  of  the  back  and  upper  wing 
coverts  ;  below  black.  Feathers  with  narrow  black  central  stripe  and  broad 
white  margin  (lacing)  constitute  nape,  hackle,  and  saddle.  Red  occurs  on 
wing  bar  and  humeral  patch.  In  the  down  plumage  Brahmas  of  both  sexes 
are  longitudinally  striped  buff  and  black. 

2.  Wing  Bars. — The  wing  bar  of  the  male  Dark  Brahma  depends  upon 
the  fact  that  the  wing  coverts  of  the  second  and  third  rows  (which  are  black 
at  the  base)  have  a  white  tip  and  a  transverse  band  of  red  in  the  middle 
between  black  and  white.  In  the  higher  coverts  and  on  the  shoulder  the 
red  still  occurs,  but  it  is  reduced  in  extent. 

3.  Comb. — The  single  comb  is  found  on  Galhis  bankiva  and  has  sometimes 
been  regarded  as  the  only  ancestral  form.  The  pea  comb  is  a  distinct  type, 
consisting  of  a  median  comb  bordered  on  each  side  by  an  accessory  comb. 
The  origin  of  the  pea  comb  is  obscure  but  certainly  ancient.  Wright  (1902, 
pp.  265,  330,  339)  contends  that  it  arose  in  the  Aseel,  a  type  of  oriental  fowl 
regarded  as  the  ancestor  of  the  Malays  and  Indian  Games  and  believed  not 
to  have  originated  from  Callus  bankiva,  but  to  represent  a  distinct  species. 
According  to  this  view  the  pea  comb  has  not  arisen  from  the  single,  but  is 
coordinate  with  it  and  of  equal  age.     From  the  ancestral  breed  it  has  become 


SINGLE-COMB    MINORCA    AND    DARK    BRAHMA.  33 

fixed  Upon  others.  Although  not  typical  of  the  Malay  breed  (which  has  a 
small  ' '  walnut ' '  comb) ,  it  often  appears  when  two  walnut  combs  are  bred 
together,*  The  pea  comb  is  found  also  in  certain  derived  races,  particu- 
larly in  the  Brahma,  and  from  this  it  has  been  engrafted  on  various  other 
breeds,  notably  on  the  Plymouth  Rock  of  America  and  on  the  so-called 
' '  Buckeyes. ' '  f 

4.  EarIvObe  Color. — Two  main  color  types  of  earlobes  are  found  in  poul- 
try, red  and  white.  The  former  occurs  in  the  Jungle  fowl,  Aseels,  Indian 
Games,  Javas,  Dorkings,  Cochins,  Brahmas,  and  other  foundation  stock  ;  con- 
sequently it  must  be  regarded  as  the  more  primitive.  The  white  earlobe 
seems  to  have  arisen  in  the  Mediterranean  type.  It  finds  its  highest  expres- 
sion in  the  White-faced  Black  Spanish.  It  has  become  a  constituent  of  the 
Houdans  and  I^a  Fleche  among  the  French  breeds  and  of  the  Hamburghs. 

5.  Iris  Color. — Among  poultry  this  ranges  from  a  gray  or  pearl  through 
yellow  to  orange,  red  and  bright  red  on  the  one  hand,  or  through  a  dirty 
red  or  bay  to  brown  and  black  on  the  other.  The  red  type  seems  to  belong 
to  the  descendants  of  the  Jungle  fowl ;  it  is  found  in  the  Jungle  fowl,  in 
most  Games,  in  most  Mediterranean  breeds,  in  most  French  fowl,  in  the 
Dorkings,  and  in  many  of  their  derivatives.  The  lighter  colors,  yellow  and 
pearl,  are  found  in  the  Aseels,  Malays,  Indian  Games,  often  in  the  Brahmas, 
attesting  their  origin  from  the  Aseel  group,  also  in  many  Cochins,  where  it 
is  said  to  be  "  very  hereditary  "  (Wright,  1902,  p.  320).  The  dark  colors — 
hazel,  brown,  and  black — are  found  in  certain  Game  fowl  of  dark  plumage, 
the  Brown-Red  Games,  the  Birchen  Games  and  the  Black  Sumatras.  They 
are  found  also  in  the  Black  Javas  of  America,  in  the  Langshans,  and  sometimes 
the  Orpingtons.  Both  the  I^angshans  and  Orpingtons  have  derived  their 
eye  color  from  the  Java,  Dark-brown  eyes  are  found  among  the  Mediter- 
ranean fowl  only  in  the  Black  Minorca  which  we  have  to  do  with  here. 
Whence  acquired  by  the  Minorca  is  uncertain  ;  possibly  indirectly  from  the 
Java.  Finally,  a  perfectly  black  iris  is  found  in  the  Silkies,  where  it  is 
probably  due  to  the  melanic  sport  that  has  made  also  skin  and  connective 
tissue  black, 

6.  Foot  Color, — This  varies  with  the  general  skin  color.  The  primitive 
color  of  the  Gallus  bankiva  group  is  an  olive,  commonly  called  ' '  willow, ' ' 
This  is  found  in  ordinary  Game  fowl.  The  Aseel- Malay-Indian  type  has 
yellow  feet.  To  this  type  belong  the  yellow  feet  of  the  Brahma  and  the 
Cochin  and  doubtless  also  of  the  American  Dominiques,  which  have  trans- 
mitted it  to  the  Plymouth  Rocks  and  Wyandottes.  Finally,  the  Leghorns 
have  bright  yellow  feet. 

By  increase  of  the  black  pigment  in  certain  birds  of  dark  plumage  there 
have  been  produced  from  the  willow  foot  the  blue,  blue-black,  and  leaden  blue 

*  Wright,  1902,  p.  325. 

t  American  Standard  of  Perfection,  1905,  p.  79. 


34  INHERITANCE    IN    POULTRY. 

feet  of  numerous  races,  e.g..  Black  Cochins,  Black  Wyaudottes,  Black  Java, 
Black  Leghorn,  Black  Minorca,  White-faced  Black  Spanish,  Hamburgh,  the 
French  fowl,  black  and  dark-colored  Games,  and  the  Silky.  By  decrease  of 
pigment  are  derived  the  white  feet  of  the  Dorkings  and  Houdans.  This 
loss  of  pigment  may  be  regarded  as  a  mutation.  It  is  associated  with  red 
or  yellow  eyes. 

Considering  the  Aseel  type  and  the  bankiva  type  as  specilically  distinct, 
the  cross  of  the  yellow  foot  and  the  blue-black  foot  in  the  present  series  is 
a  cross  between  specific  characteri.stics. 

7.  Foot  Feathering. — In  Gallics  bankiva  and  in  the  Aseel-Malay  group 
the  feet  are  without  boots.  The  same  is  true  of  the  Game  fowl,  although 
minute  feathers  are  sometimes  found  on  their  feet.  Foot  feathering  is 
found  among  various  species  of  birds ;  among  scratching  birds,  in  grouse, 
ptarmigans  {Tctrco,  Bmasia,  Lagopus),  among  some  pigeons,  and  the  owls. 
Typically  absent  from  the  Gallinae,  it  ha^  cropped  out  in  the  Brahma,  Cochin, 
and,  probably  independently,  in  the  Silky  and  Sultan.  In  these  groups  it 
has  been  preserved  because  of  its  importance  in  brooding  or  because  it  has 
struck  the  fancier's  eye, 

8.  Vulture  Hock. — This  consists  of  long  stiff  quill  feathers  projecting 
backward  at  the  heel  joint.  It  is  found  among  poultry  only  in  the  Cochin- 
Brahma  group  and  its  derivatives.  This  characteristic  is  a  good  example  of 
a  progressive  variation. 

MATERIAI,. 

The  cock  used  in  this  cross,  No.  122  (fig.  19),  was  a  bantam  Dark  Brahma, 
weighing  1,900  grams,  received  (February,  1905)  from  F.  H.  Hodges,* 
Red  Bank,  New  Jersey,  who  is  a  successful  breeder  of  this  variety.  The 
cock  is  typical  of  his  kind. 

The  hens  w^ere  four  Single-comb  Black  Minorcas,  Nos.  14  (fig.  3),  16,  18, 
and  28,  of  which  the  three  former  were  purchased  of  Mr.  George  C.  Kly  in 
July,  1904,  and  No.  28  was  hatched  at  the  station  in  August,  1904,  from 
one  of  the  purchased  hens  mated  with  the  full-blooded  Minorca  cock  No.  12. 

REvSULTS. 

Only  the  first  generation  of  hybrids  has  been  reared  up  to  the  time  of 
writing. 

I.  General  Plumage  Color. — In  all  cases  (41)  the  hybrids  are  prevail- 
ingly black.  Usually  the  feathers  of  the  occiput  and  nape  are  laced  with 
white,  much  more  in  the  males  than  in  the  females,  and  the  hackles  of  the 
male  are  obscurely  barred  or  splashed  with  white  (fig.  21).  Evidently  the 
white  lacing  of  the  Dark  Brahma  is  trying  to  assert  itself.  The  color  of  the 
wing  coverts  is  considered  in  the  next  paragraph.     The  down  of  the  young 


Foot  marked  "  F.  H.  H.,  164." 


SINGLE-COMB    MINORCA    AND    DARK    BRAHMA,  35 

is  dead-black,  being  without  the  longitudinal  stripes  of  the  Dark  Brahma 
young,  and,  for  the  most  part,  without  the  white  wing  feathers  and  ventral 
aspect  of  the  young  Minorca.  Nevertheless,  exceptionally,  one  finds  the 
chin  and  part  of  the  throat  of  the  young  white,  the  head  feathers  may  be 
tipped  with  white,  and  in  one  or  two  instances  a  little  white  occurs  on  the 
wing.  The  young  plumage  seems  to  be  a  neomorph,  but  on  the  whole  it 
belongs  rather  to  the  Minorca  type  than  to  the  more  primitive  Game  type 
of  juvenile  coloration. 

2.  Wing  Covkrts. — In  14  grown  male  hybrids  of  which  I  have  records,  a 
more  or  less  prominent  wing  bar,  formed  by  black,  red,  and  straw-colored 
feathers  in  the  third  or  fourth  row  of  wing  coverts,  occurs  (figs.  20,  21). 
The  five  females  are  wholly  black,  but  even  in  these  the  wing  coverts  are 
barred  with  an  iridescent  purple  black  ;  consequently  a  disturbance  of  the 
coloration  of  the  wing  coverts  may  be  said  to  be  typical  of  the  hybrids.  The 
wing  bar  of  the  Dark  Brahma  male  dominates  over  the  black  wing  of  the 
Minorca,  but  it  dominates  imperfectly. 

3.  Comb. — In  all  cases  the  pea  comb  of  the  Brahma  dominates  over  the  single 
comb.  Critical  examination  shows,  however,  that  the  pea  comb  of  the 
hybrid  is  not  always  typical.  Frequently  the  whole  structure,  and  espe- 
cially the  median  ridge,  is  abnormally  high  (fig.  21),  and,  on  the  other  hand, 
in  a  few  cases  the  lateral  ridges  are  hard  to  make  out.  The  dominance  is 
imperfect.* 

4.  Karlobe  Color. — The  earlobe  in  every  case  contains  both  white  and 
red.  The  result  is  not  a  blend,  however,  but  is  particulate,  the  white 
appearing  at  the  center.  As  red  is  rarely  wholly  absent  from  the  Minorca's 
eariobes,  whereas  white  is  wholly  absent  from  that  of  the  Dark  Brahma,  it 
may  be  possible  to  bring  inheritance  of  earlobe  color  under  the  general 
formula  and  speak  of  the  white  earlobe  as  being  imperfecth^  dominant. 

5.  Iris  Color. — The  iris  of  the  hybrid  is  yellow,  rarely  with  a  trace  of  red 
or  reddish  brown.  The  type  of  the  Dark  Brahma  is  dominant,  but  imper- 
fectly so. 

6.  Beak  and  Foot  Color. — This  is  always  black  in  the  hj-brid.  However, 
the  black  is  rarely  the  blue-black  of  the  Minorca,  but  it  is  usuall}-  a  brownish 
black  frequently  tinged  with  yellow,  particular!}'  on  the  under  side  of  the 
toes.     Black  is  imperfectly  dominant. 

7.  Foot  Feathering. — In  all  cases  the  hybrids  have  feathering  on  the  feet. 
In  many  cases  this  is  clearly  reduced  in  amount  from  what  is  found  in  the 
Dark  Brahma.     Foot  feathering  is  imperfectly  dominant  (fig.  20). 

8.  Vulture  Hock.  —This  is  absent  in  every  case,  although  about  a  quarter 
of  the  cases  show  the  feathers  of  the  heel  much  larger  and  more  removed 


*  The  inheritance  of  the  pea  comb  of  the  Dark  Brahma  has  not  been  considered  in  the 
recent  studies  of  others.  The  pea  comb  of  the  Indian  Game  is  found  by  Bateson  and 
Saunders  (1902,  p.  94)  to  be  imperfectly  dominant  over  the  single  comb  of  the  White 
Leghorn. 


36 


INHERITANCE   IN   POULTRY. 


from  the  foot  thau  in  the  Minorca.     Plain  feathered  heel  is  dominant,  but 
not  perfectly  so. 

CONCLUSIONS. 

This  series  of  experiments  is  only  begun.  Conclusions  as  to  dominance 
are  tentative  until  tested  in  the  second  hybrid  generation.  The  Minorca 
characteristics  appear  to  dominate  in  (i)  general  black  color,  (4)  white  ear- 
lobes,  (6)  black  foot  and  beak,  and  (8)  absence  of  vulture  hock.  Dark 
Brahma  characteristics  appear  to  dominate  in  (2)  wing  bar,  (3)  pea  comb, 
(5)  yellow  iris,  and  (7)  foot  feathering.  In  every  case,  however,  dominance 
is  imperfect.  In  some  cases,  at  any  rate,  (5,  7\  it  is  the  new,  additional, 
or  positive  characteristic  that  dominates. 

Series  Vi.— White  Leghorn  and  Dark  Brahma. 
STATEMENT  OF  PROBLEM. 

THE  RACES  AS  A  WHOLE. 

It  is  proposed  to  investigate  the  behavior  of  characteristics  when  the  heavy- 
bodied,  short  and  stout  legged,  loose-feathered,  dark-colored  Asiatic  type  is 
crossed  with  the  slender,  tall-legged,  close-feathered,  white  Mediterranean 
type.  Both  types  are  ancient,  but  the  Brahma  must  be  regarded  as  nearer 
its  ancestral  form,  Aseel-Malay-Indian,  than  the  Leghorn  is  to  the  Jungle 
fowl. 

TABI^E   OF   CHARACTERISTICS. 


No. 


3 

4 
5 
6 

7 
8 

9 
10 


Characteristic. 


Hackle  color. 
Wing  bar 


Wing  bow. 
Tail  color . 

Comb  . 

Earlobe... 


Iris  color     

Vulture  hock.. . . 
Foot  feathering. 
General  form. .  .  . 


White  Leghorn. 


Dark  Brahma,  female. 


White   

White 

White   

White. 

Single  (page  19) 
White,  red-edged 

(page  33). 
Red  (page  33)  .. 

Absent 

Absent  .... 
Narrow,  slender. 


Straw,  black-penciled. 
Buff,  black -penciled   . 


Dark  Brahma, 
male. 


Buff,  black-penciled   . 
Black,  straw-penciled. 

Pea  (see  page  32). 

Red  (see  page  33). 


Black,  straw- 
laced. 

Black,  red,  and 
white. 

Black  and  white. 

Greenish  black. 


Yellow  (see  page  33). 
Present  (see  page  34). 
Present  (see  page  34). 
Broad,  chunky. 


REMARKS  ON  THE  CHARACTERISTICS. 

I.  Hackle  Color. — Among  most  poultry  that  are  of  broken  color  the 
hackle  feathers  are  unlike  those  of  the  rest  of  the  plumage.  They  have  a 
dark  center  and  a  lighter  lacing.  In  the  Malays  and  Indians  they  have  a 
red  center  edged  with  green.  In  the  Galhis  bankiva  female  the  hackles  have 
a  black  center  (with  straw-colored  shafting)  and  straw-colored  lacing.  This 
is  the  type  of  hackle  feather  found  in  the  male  Dark  Brahma.      It  is  found, 


WHITE    LEGHORN    AND    DARK    BRAHMA. 


37 


in  both  sexes,  among  man^^  other  breeds.  The  hackle  of  the  female  Dark 
Brahma  (fig.  i8)  differs  from  that  of  the  male  in  that  the  broad  black  center 
is  barred,  or  penciled,  with  straw  color. 

3.  Wing  Bow. — The  wing  <Jar  is  described  for  the  male  at  page  32.  In  the 
male  Dark  Brahma  the  feathers  of  the  fourth  and  higher  rows  of  wing  coverts 
have  their  distal  halves  white  forming  the  wing  bow.  No  such  distinct  wing 
bar  and  wing  bow  occur  in  the  female,  the  feathers  of  this  region  being 
uniformly  penciled  like  the  others. 

MATERIAIv. 

There  are  two  sets  of  experiments  in  this  series.  In  the /irs/sei  the  mothers 
were  White  heghora.  Bantams,  Nos.  127  and  128,  probabh^  heterozj-gotes 
with  black,  further  discussed  at  page  39.  The  paternal  Dark  Brahma, 
No.  122,  has  been  already  referred  to  at  page  34.  In  the  second  set  the 
mother  was  Dark  Brahma,  No.  121.  She  has  the  same  history  as  No.  122. 
She  is  a  prettily  penciled  bird  (fig.  18).  The  father  was  White  Leghorn 
Bantam,  No.  126,  described  at  page  39. 

RESULTS. 

Of  the  first  set  19  offspring  are  recorded,  including  8  in  the  shell.  Females 
8,  males  5.  Of  the  second  set  27  are  recorded,  including  8  in  the  shell. 
Females  14,  males  4. 

I.  General  Plumage  Color. — The  result  differs  in  the  two  sets  and  the 
two  sexes,  and  it  is  otherwise  variable. 


Plumage  color. 


Nearly  pure  white 

White  +  much  black 
and  red  pigment  as 
barring: 

Like  Dark  Brahma  fe- 
male  

Barred 

Black  or  nearly  so 


Females. 

Males. 

• 

Unknown  sex. 

First     Second 
set.         set. 

Total. 

First 
set. 

Second 
set. 

Total. 

First 
set. 

Second 
set. 

i 
Total. 

4              3 

0               0 

4      j        3 
0      1        3 

0              5 

7 

0 

*7 
3 
5 

3 

2 

0 
0 
0 

2 

0 

0 
2 

0 

5 

2 

0 

2 
0 

7 

II 

2 

X8 

2 

Total. 


30 


The  results  are  explicable  on  the  hypothesis  that  all  of  the  White  Leg- 
horn Bantams,  Nos.  126  $  ,  127  9,  and  128  ?,  contain  white  gametes  and 
also  gametes  bearing  red  pigment,  black  pigment,  and  the  barred  pattern, 

3.  Wing  Coloration. — In  the  first  set  the  wing  coloration  is  like  that  of 
the  plumage  in  general,  except  that  in  the  females  marked  like  the  Dark 
Brahma  the  coverts  contain  much  red  (fig    23). 

Second  set.  Of  7  prevailingly  white  hybrids  three  show  red  or  buff  on  the 
wings ;  t  of  the  5  black-and-white  (penciled)  birds  all  but  one  show  red  or 
purple  on  the  wings  ;  of  two  adult  black  hybrids  one  shows  buff.     Three  other 


*Fig.  23. 


t  Fig.  25,  Plate  viil. 


38  INHERITANCE   IN   POULTRY. 

females  are  marked  like  the  Dark  Brahma  female.  Red  pigment  is  com- 
moner in  this  set,  with  White  Leghorn  father,  than  in  the  first  set,  with 
Dark  Brahma  father.  This  speaks  for  the  hypothesis  that  red  has  come 
from  the  White  Leghorn,  as,  according  to  usual  e  xperience,  the  father  tends 
to  determine  coloration. 

4.  Tail  Color. — First  set.  Of  1 1  offspring,  8  have  a  white  tail,  the  prevail- 
ing color  of  the  body  ;  in  one  case  the  tail  is  white  except  for  one  black 
feather,  and  in  two  cases  it,  like  the  body  in  general,  agrees  with  the  Dark 
Brahma  female  in  being  black  with  buff  penciling  (fig.  23). 

Second  set.  Of  15  hybrids,  6  are  nearly  or  wholly  white  on  the  tail,  one 
has  two  black  feathers,  5  are  black,  two  are  black-and-white  barred,  and 
one  is  black  with  buff,  as  in  the  Dark  Brahma  female.  The  tail  color  tends 
to  resemble  that  of  the  general  body. 

5.  Comb  Form. — In  all  cases  of  adult  hybrids  of  either  set,  the  comb  is  pea 
(fig.  24).     Pea  comb  is  consequently  here  also  dominant  over  single  comb. 

6.  Earlobe. — Both  the  Brahma  solid  red  and  ths  White  Leghorn  white, 
red-margined  earlobes  appear  in  about  equal  numbers.  It  is  probable  that 
my  heterozygous  White  Leghorn  bantams  have  been  early  crossed  with  some 
red-lobed  race. 

7.  Iris  Color. — This  is  definitely  established  only  in  mature  birds.  All 
eyes  show  more  red  than  the  Dark  Brahma  and  the  tendency  is  to  redden  with 
age  ;  consequently  red  is  probably  dominant. 

8.  Vulture  Hock. — This  is  absent  in  all  cases  (fig.  22).  One  hybrid 
has  the  hock  feathers  a  little  elongated.  Short  feathering  at  the  heel  is 
dominant. 

9.  Foot  Feathering. — I^irst  set.  Of  19  hybrids  having  the  Dark  Brahma 
father,  3  uuhatched  chicks  are  recorded  as  non-booted.  Of  the  remainder,  8 
are  slightly  or  very  slightly  booted.  Three  adults  have  a  medium  covering 
of  feathers  on  the  foot.  The  Brahma  tendency  toward  booting  has  been 
diluted  by  the  cross  with  the  Leghorn. 

Second  set.  Of  24  offspring  of  Dark  Brahma  mother,  all  have  well-devel- 
oped boots.  This  constitutes  a  striking  case  of  a  dijjererice  in  reciprocal 
crosses.  Booting  is  probably  here,  as  elsewhere,  dominant,  but  frequently 
very  imperfectly  so. 

CONCLUSIONS. 

Of  the  nine  characteristics,  the  following  exhibit  clear  alternative  inherit- 
ance, the  dominant  characteristic  being  printed  in  italics  : 
Pea  comb  vs.  single  comb. 
No  vulture  hock  vs.  vulture  hock. 
Booted  foot  vs.  unbooted  (when  Brahma  is  mother). 
The  other  characteristics  can  not  for  one  reason  or  another  be  so  easily 
classified.     The  red  of  the  wing  bar  seems  to  behave  like  a  unit  character 
and  is  independent  of  the  coloration  of  the  rest  of  the  body. 


BLACK    COCHIN   AND   WHITE   LEGHORN. 


39 


The  inheritance  of  booting  is  peculiar  in  that  in  the  first  set,  Leghorn 
mother  and  Brahma  father,  the  booting  fails  to  show  that  clear  dominance 
which  is  almost  universal  ;  yet  I  can  hardly  suspect  the  purity  of  the  Dark 
Brahma  male.  It  would  seem  that  in  this  series  also  the  mother  transmits 
booting  more  .strongly  than  the  father. 

Series  VI  I. — Black  Cochin  Bantam  and  White  Leghorn  Bantam. 
STATEMENT  OF  PROBLEM. 

This  experiment  was  undertaken  to  learn  the  method  of  inheritance  where 
one  parent  is  pure  white  and  the  other  pure  black. 

THE  RACES  AS  A  WHOLK. 

The  Black  Cochin  Bantam,  also  called  Black  Pekin,  is  a  diminutive  of  the 
Cochin  (fig.  26).  It  is  stated  by  Wright  (1902,  p.  499)  that  the  Pekins 
came  in  i860  from  the  city  of  that  name.  The  original  color  was  buff  ;  the 
black  has  probably  been  engrafted  on  the  race  by  a  cross  with  some  small 
black  race.  The  Cochins  are  closely  allied  to  the  Brahmas  and  share  with 
them  a  chunky  form,  stout  and  densely  feathered  feet  and  red  face  and  ear- 
lobes.     The  White  Leghorn  has  been  discussed  at  page  18. 

TABLE  OF   CHARACTERISTICS. 


No. 

Characteristic. 

Black  Cochin 
Bantam. 

White  Leghorn 
Bantam. 

I 
2 

3 

4 

General  plumage  color. 
Earlobe  color 

Black 

Red 

White. 

White,  with  trace  of  red. . 

Absent. 

Absent. 

Vulture  hock 

Present 

Foot  feathering 

Present 

REMARKS  ON  THE  CHARACTERISTICS. 

1.  General  Plumage  Color. — In  the  Black  Cochin  this  is  a  deep 
greenish  black.     No  trace  of  white  appears  anywhere. 

2.  Earlobe  Color. — In  the  Black  Cochin  this  is  of  the  dark  red  or  bay 
characteristic  of  all  the  Aseel- Malay  group. 

3.  Vulture  Hock. — This  is  well  developed  in  the  Black  Cochin  (see 

page  34). 

MATERIAL. 

The  mothers  were  four  Black  Cochin  Bantams, -^^  very  similar,  each  heavily 
booted  and  weighing  about  600  grams  apiece.  Trap  nests  were  not  used, 
but  owing  to  special  peculiarities  the  eggs  of  the  separate  mothers  were  dis- 
tinguished as  A,  B,  C,  and  D. 

The /rt;///(?r  was  a  White  Leghorn  Bantam,  No.  126,  purchased  Januar>', 
1905,  from  the  Cyphers  Incubator  Compan3%  together  with  two  hens  (Nos. 

*Nos.   129,   130,   131,   132,  received  February,  1905,  from  Mr.  H.  B.  Kutschbach  (fig. 
26,  pi.  ix). 


40 


INHERITANCE    IN   POULTRY. 


127,  128).  Mated  with  the  hens,  nine  young  were  produced.  Four  of 
these  were  typical  White  lyeghorns  without  black  ;  three  others  were  white 
except  that  black  feathers  occasionall}-  appeared.  One  (No.  213)  was 
nearly  solid  black  and  one  (No.  229)  was  black  with  nearly  every  feather 
barred  with  white.  It  is  plain  that  the  strain  I  have  has  not  been  wholly 
purified  of  black.  This  is  indicated  also  by  the  fact  that  No.  128  has  every 
feather  peppered  with  black — a  heterozygous  form  of  coloration. 

RESULTS. 

1 .  General  Plumage  Color. — Of  26  hybrids,  1 1  were  pure  white  or  had 
only  a  little  black  ;  7  were  black,  sometimes  with  a  little  white,  and  8  were 
barred  black  and  white  (fig.  27).  The  results  confirm  the  view  that  White 
Leghorn  Bantan  No.  126  (?  has  black  germ  cells.  The  barred  condition  is 
unexpected  and  is  probably  recessive  in  the  White  Leghorns. 

2.  Earlobp:  Color. — In  all  cases  ( 10)  of  adults  but  two,  the  earlobe  is  red  ; 
in  the  remaining  two  some  white  is  mixed  with  the  red.  The  red  earlobe 
is  probably  dominant,  but  imperfectlj^  so. 

3.  Vulture  Hock, — Out  of  13  cases  n  have  clearly  no  vulture  hock  and 
two  show  a  slight  enlargement  of  the  heel  feathers.  Vulture  hock  is  prob- 
ably recessive. 

4.  Foot  Feathering. — Every  hybrid  is  booted,  but  the  booting  is  less 
heavy  than  in  the  Dark  Brahma  (fig.  27).  Booting  may  be  dominant,  but 
it  is  not  perfectly  so. 

CONCLUSIONS. 

The  male  parent  is  heterozygous  and  probably  contains  at  least  three  sorts 
of  gametes,  viz,  pure  black,  pure  white,  and  barred,  the  last  being  a  mosaic* 
The  black  of  the  mother  is  recessive  to  all  of  these.  The  occurrence  of  barred 
mosaic  is  of  interest,  but  it  is  of  unknown  origin.  The  ancestral  red  ear-color 
and  the  new  ' '  booting  ' '  are  both  dominant.  Dominance  is,  however,  im- 
perfect. 

Series  VIII. — White  Leghorn  Bantam  and  BufF  Cochin  Bantam. 

STATEMENT  OF  PROBLEM. 

This  series  was  undertaken  to  determine  the  method  of  inheritance  of 
buff  when  combined  with  a  white  plumage  coloration. 

THK  RACES  AS  A  WHOLE. 

The  White  Leghorn  Bantam  has  been  described  at  page  39.  The  Buff 
Cochin  Bantam  (fig.  28)  is  a  diminutive  Buff  Cochin,  which  resembles  in 
form  the  Black  Cochin  (p.  39).  Cochins  as  we  know  them  to-day  (the 
name  was  formerly  applied  to  a  different,  now  extinct,  race)  seem  to  have 
been  imported  into  this  country  and  also  into  England  from  eastern  China 


*  Castle  and  Allen,  1903,  p.  606. 


WHITE   LEGHORN   AND   BUFF   COCHIN. 


41 


in   the  year   1847.     The  earliest    importations    were   buff.     According  to 
McGrew  (1904,  p.  526)  : 

la  many  of  these  retreats,  mi-au<i  or  monasteries,  thousands  of  specimens  of  Buff  and 
Partridge  China  (Cochin)  fowls  are  annually  raised,  and  in  other  places  the  colors  are 
mixed.  The  Kinkee  (gold  flower)  colored  birds  are  the  most  esteemed,  both  as  regards 
antiquity  and  purity.  .  .  .  Hoangho  is  the  oldest  [of  the]  ini-aus,  and  its  records  show 
that  this  same  race  of  fowls  was  cultivated  by  the  brotherhood  1,500  3-ears  ago. 

Buff  and  Partridge  Cochins  are  indigenous  to  the  temperate  and  more  southerly  por- 
tions of  the  empire.  This  is  corroborated  by  naturalists  and  travelers.  Mr.  Gabb,  the 
well-known  English  naturalist,  says  :  "According  to  my  view,  a  black  or  white  Cochin  is 
an  improbability,  if  not  an  impossibility,  as  a  natural  product  of  a  tropical  or  subtropical 
region.  The  natural  color  of  the  feathers  of  the  poultry  in  the  zone  of  Cochin  China 
would  be  buff  or  yellow,  or  some  of  the  varieties  of  these  colors,  but  never  black  or 
white,  except  by  accidental  variation." 

Other  testimony  presented  by  the  same  author  is  of  the  same  sort  and 
establishes  the  fact  that  Buff  Cochins  are  a  primitive,  foundation  race  of 
great  antiquity. 

TABt,E   OF   CHARACTERISTICS. 


No. 

Characteristic. 

White  Leghorn. 

Discussed 
at  page — 

Buff  Cochin. 

Discussed 
at  page — 

I 
2 

General  color 

Earlobe  color 

Vulture  hock 

Foot  feathering 

White 

White 

Absent 

19 

33 

Buff 

Red 

Present 

Present. . . . 

41 
33 
34 
34 

4 

Absent 

REMARKS  ON  THH  CHARACTERISTICS. 

I.  General  Plumage  Color. — The  buff  color  of  the  Cochin  is,  as  has 
been  shown  above,  of  high  antiquity.  From  the  Buff  Cochin  it  has  been 
transferred  to  many  other  breeds  by  crossing.  Thus  there  are  Buff  Wj-^an- 
dottes,  of  which  McGrew  says  (1901,  p.  24):  "  Two  distinct  lines  were  pro- 
duced under  different  methods.  One  was  formed  from  Wyandotte-Buff 
Cochin  cross  ;  the  other  came  through  the  Rhode  Island  Red- Wyandotte 
cross."  The  Rhode  Island  Red  is,  however,  as  is  well  known,  a  direct 
descendant  of  the  Buff  Cochin.  The  Buff  Plymouth  Rocks  were  derived 
directly  or  indirectly  from  the  Buff  Cochin  (McGrew,  1901,  p.  25).  The 
history  of  the  Buff  Leghorn  is  the  same — the  offspring  of  a  yellow  Danish 
lyCghorn  cock  and  Buff  Cochin  pullets  mated  with  a  yellow  Leghorn  hen. 
The  produce,  three-fourths  Yellow  Leghorn  and  one-fourth  Buff  Cochin, 
gave*  "the  first  Buff  Leghorns  ever  shown."  The  Buff  "  Orpingtons  " — 
a  highly  modern  and  mongrel  breed — have  a  similar  history,  being  chiefly 
Buff  Cochin  and  Dorking  (Wright,  1902,  p.  296). 

The  origin  of  the  buff  as  it  occurs  in  the  Cochins  can  only  be  guessed  at  ; 
but  there  are  important  facts  to  be  considered.  First,  it  appears  that  the 
buff  color  is  very  inconstant  even  in  China.     Says  a  traveler  :   ' '  No  two  can 

*Wyckoff,  1904,  p.  527. 


42 


INHERITANCE   IN   POULTRY. 


be  found  of  exactly  the  same  color  ;  some  are  a  chestnut  color,  others  darker, 
and  some  quite  light  "  (McGrew,  1901,  p.  527).  Of  the  Buff  Cochins  as 
first  imported  to  England,  Wright  (1902,  p.  245)  says:  "  The  buff  colors 
were  much  subdivided,  ranging  from  the  lightest  silver  buff  and  silver  cin- 
namons through  lemons  and  buffs  to  the  deep  colored  cinnamons  which 
would  now  be  called  almost  red.  Originally,  also,  the  birds  were  not 
uniformly  buff  over  the  whole  body  ;  even  prize-winners  were  such  as  would 
now  be  called  '  tricolored,'  the  breast  being  lemon  or  orange  buff,  the 
hackles  and  saddle  much  darker,  and  the  wing  darker  still,  even  a  red." 
From  all  of  this  it  is  plain  that  buff  is  only  a  diluted  form  of  red — a  color 
that  is  abundant  in  the  plumage  of  the  Malay  and  Indian  breeds,  and  the 
replacement  of  all  black  by  this  buff  is  probably  due,  originally,  to  a  xanthic 

"sport." 

MATERIAL. 

The  ynother  was  the  White  lyeghorn  Bantam  No.  128,  a  heterogametous 
bird,  already  discussed  at  page  40.  T\\q  father  was  a  Buff  Cochin  Bantam, 
No.  545  (fig.  28),  original  stock,  of  whose  ancestry  nothing  is  known. 

RESULTS. 

I.  General  Plumage  Color. — Thirty-one  offspring  show  the  following 
distribution  of  color :  White,  9  ;  white  and  buff,  9  ;  white  and  black,  4  ; 
white,  black,  and  buff,  2  ;  black  and  buff,  4  ;  black  (all  juvenile),  3. 

Calling  the  germ  cells  of  the  mother  equally  white  and  white-and-black 
and  regarding  the  buff  as  (imperfectly)  recessive  when  paired  with  white, 
we  have — 


Characteristic. 

/. 

Percentages. 

Actual. 

Expecta- 
tion. 

White  (and  buff) 

18 
13 

58.1 
41.9 

50 
50 

White-and-black  (and  buff) 

Total 

31 

TOO  0 

loo 

Of  the  white  and  buff  heterozj'gotes,  white  only  appears  in  9  ;  the  remainder 
show  some  buff.     White  is  dominant,  but  imperfectly  so.* 

Wright  (1902,  p.  244)  states  in  regard  to  crosses  between  white  and  buff 
Cochins  that  in  the  early  days  they  "bred  most  amazingly  in  regard  to 
color.  .  .  .  From  one  brood  of  ten  chickens  of  this  cross  two  pullets  were 
pure  black  ;  two  pullets  and  three  cockerels  black  with  more  or  less  gold  in 
the  hackles,  and  marked  wings  ;  the  other  three  darkly  penciled  birds." 

Hurst  (1905,  p.  134)  finds  that  cro.sses  between  White  Leghorn  female 
and  Buff  Cochin  male  (essentially  the  same  crosses  as  mine)  gave  60  chicks — 


*But  see  fuller  discussion  of  the  heterozygous  nature  of  my  White  Leghorns,  page  40. 


TOSA    POWI.   AND    WHITE    COCHIN.  43 

' '  53  whites  aud  7  buffs.  Of  these  2  were  apparently  clear  whites  and  5 1  white 
patched  with  buff  and  brown,  chiefly  on  the  head,  neck,  and  breast  (18  of 
these  were  also  oddly  black-ticked) ;  the  7  buffs  were  all  more  or  less  patched 
white."  Hurst  concludes  that  the  white  plumage  color  of  the  I^eghorn  is 
dominant  over  the  Cochin  buff,  but  that  this  dominance  is  incomplete  in  the 
majority  of  cases.  He  adds  :  "  In  F,  the  dominance  of  both  white  and  black 
over  buff  is  much  less  complete  than  that  of  white  over  black." 

2.  Earlobe  Color. — In  all  recorded  cases  the  hybrids  have  a  red  earlobe, 
sometimes  with  a  lighter  colored,  even  yellowish,  center. 

3.  Vulture  Hock. — This  is  always  absent  in  the  hybrids.  However,  two 
cases  show  an  elongation  of  the  heel  feathers. 

4.  Foot  Feathering.  — In  all  cases  the  ' '  boot ' '  of  the  hybrid  was  reduced 
as  compared  with  the  Cochin  parent.  In  3  cases  out  of  31  no  trace  of 
feathers  could  be  detected  on  the  tarsus. 

CONCLUSIONS. 

Bufi  is  recessive  toward  white,  but  the  dominance  of  white  is  very  im- 
perfect, so  that  we  may  have  various  degrees  of  buffness  in  the  hybrids. 
Black,  or  the  mosaic  black-white,  appears  to  dominate  over  buff,  but  here 
again  the  dominance  is  frequently  imperfect.  Imperfect  dominance  is  not 
revealed  by  a  blending,  but  by  sprinkling  of  the  red  pigment. 

The  earlobe  color  of  the  Cochins  (  A.seel  type)  dominates  over  that  of  the 
Leghorn,  but  not  perfectly.  Vultitrc  hock  is  recessive,  but  not  always  per- 
fectly so.  Foot  feathering  may  be  said  to  be  imperfectly  dominant.  But 
this  case  is  of  special  interest  because  the  result  is  practically  a  blend. 
Hurst  (1905,  p.  134)  similarly  states  that  out  of  60  chicks  from  his  cross,  all 
had  feathered  ' '  shanks, "  "  but  in  every  case  the  length  or  number  of  feathers 
was  reduced  to  about  one-half." 

Series  IX. — Tosa  Fowl  (Yokohama)  and  White  Cochin  Bantam, 

STATEMENT  OF  PROBLEM. 

This  series  of  experiments  was  undertaken  in  the  first  instance  to  test  the 
inheritance  of  the  long-tailed  characteristic  of  the  Japanese  long- tailed  fowl 
(variously  called  Tosa   fowl,   Yokohama,    Phoenix   fowl,    Japanese  Game 
Shinowara-to,  etc.). 

THE  RACES  AS  A  WHOLE. 

The  Tosa  fowl*  (figs.  29,  31)  has  long  been  bred  in  Japan  and  plays  a 


*  Professor  Mitsukuri  on  the  occasion  of  a  recent  visit  to  the  Station  for  Experimental 
Evolution  informed  me  that  in  Japan  these  birds  are  known  as  Tosa  fowl,  since  they  were 
originally  bred  in  the  province  of  that  name,  particularly  at  Shinowara.  He  further  re- 
marked that  the  feudal  chief,  or  daimio,  of  that  province  had  as  his  emblem  or  insignia 
a  spear  with  a  long  cock's  feather  on  it,  and  he  made  the  interesting  suggestion  that  the 
activity  of  the  fanciers  hid  been  stimulated,  not  only  by  their  satisfaction  in  long-tailed 
birds,  but  also  by  the  desire  of  meeting  the  ever-increasing  ideals  of  their  chief  as  to  the 
length  of  the  feather  of  his  insignia. 


44 


INHERITANCE    IN   POULTRY. 


prominent  part  in  Japanese  art.  Ou  the  authority  of  Chamberlain  (1900), 
"  as  great  a  length  of  tail  as  18  feet  has  been  reached  in  the  tail  feathers, 
but  even  12  feet  is  a  rarity.  From  7  to  8  or  11  feet  is  the  usual  length." 
Aside  from  the  tail,  the  fowl  has  remarkably  long  hackle  and  saddle  feathers 
of  a  golden  color.  Otherwise  it  closel}'  approaches  the  European  black- 
breasted  Red  Game,  having,  like  it,  retained  most  of  the  coloration  of  Gallus 
bankiva. 

The  Cochin  fowl  was  used  in  the  mating  because  its   tail   feathers  are 
notoriously  short  and  consequently  afford  a  strongly  opposed  allelomorph. 

tablk  of  charactrristics. 


No. 

Characteristic. 

Tosa  fowl. 

White  Cochin 
Bantam. 

I 
2 
3 
4 

General  color 

Tail 

Foot  feathering 

Foot  color 

Dark 

Long 

Absent 

Willow 

White. 
Short. 
Present. 
White. 

REMARKS  ON  THE  CH.A.RACTERISTICS. 

1.  General  Plumage  Color. — The  colors  of  the  male  Tosa  fowl*  are  very 
striking.  The  head  is  black  ;  the  feathers  of  the  nape  and  the  hackles  are 
black  proximateh^  but  the  exposed  portion  is  red,  becoming  a  deep  mahogany 
on  the  middle  of  the  back.  The  long  saddle  feathers  are  green  laced  with 
mahogany.  The  tail  feathers  are  solid  greenish-black.  The  breast,  belly, 
and  under  tail  coverts  are  black.  The  remiges  are  black,  edged  exteriorly 
with  red.  The  coverts  are  black  tipped  with  mahogany  in  varying  amount, 
but  so  as  to  produce  a  marked  red  wing  bar.  The  female  Tosa  fowl  (fig.  30) 
has  a  black  head  and  nape  and  golden  hackles.  The  feathering  of  the  back 
and  saddle  and  the  wing  coverts  are  black  mossed  with  rusty  and  have  a 
straw-colored  shaft.  The  breast  is  strongly  tinged  with  buff.  The  White 
Cochhi,  on  the  other  hand,  is  pure  white  (fig.  32). 

2.  Tail. — The  question  of  the  origin  of  the  long  tail  is  of  great  importance. 
Any  light  on  this  question  would  illuminate  the  problem  of  specific  differ- 
entiation and  the  origin  of  specific  characteristics  in  general. 

Hypotheses.  In  accordance  with  current  theories  of  specific  differentiation 
we  have  to  recognize  that  this  characteristic  may  have  arisen  : 

(i)  As  a  mutation.  As  such  it  would  be  brought  into  the  same  category 
with  frizzled  feathers  or  the  cerebral  hernia  of  Polish  fowl.  Professor  E.  Ray 
lyankester  has  referred  to  the  condition  as  a  sport. 

(2)  As  the  result  of  selection.  This  would  be  the  most  popular  explana- 
tion. Romanes  (1901,  p.  302,  fig.  95)  includes  this  case  as  one  of  a  number 
of  typical  proofs  of  the  efficiency  of  artificial  selection.  Weismann  (1904, 
II,  pp.  124,  326)  states  definitely  that  the  long  tail  is  due  to  selection.     The 

*  Fig.  29,  Plate  X. 


TOSA   FOWL   AND   WHITE   COCHIN.  45 

underlying  assumption  in  both  cases  is  that  the  selection  has  been  of  minute 
favorable  fluctuations  rather  than  the  conservation  of  sports.  This  is  a 
conceivable  hypothesis. 

(3)  As  a  result  of  functional  hypertrophy  of  the  feather  follicle.  By 
artificial  treatment  the  blood  supply  to  the  follicles  might  be  stimulated  so 
as  to  make  the  feather  grow  longer.  Such  an  effect  might  be  inherited  or 
not,  as  could  be  determined  by  breeding.  If  the  offspring  of  the  long-tailed 
fowl  have  a  long  tail,  though  untreated,  then  we  would  have,  on  the  third 
hypothesis,  an  inheritance  of  an  acquired  character.  Cunningham  (1903) 
believes  that  the  Tosa  fowl  is  a  demonstration  of  such  inheritance. 

Growth  of  tail  feathers.  The  study  of  the  long  tail  of  the  Tosa  fowl  leads 
us  to  consider  the  whole  matter  of  feather  growth  and  of  the  anatomy  of  the 
tail.  In  early  months  of  their  life  chicks  are  constantly  losing  old  feathers 
and  gaining  new  ones  built  on  a  larger  scale  to  meet  the  needs  of  the  enlarg- 
ing body.  Later,  these  feathers  _ 
are  all  molted  during  one  period  .'  ^'"-^o.t. 
in  the  autumn.  During  develop-  a'j^  '•*'  ^  ^^^a, 
ment,  the  tip  of  the  feather  is  O  d>,  ^ 
formed  first  and  growth  continues  ^^  n  ^^p' 
at  the  base,  within  a  sheath,  for  a       ,;      ^    /^3Q 


shorter  orlonger  period,  depending       ^^  q^,   Q 
on  the  eventual  size  of  the  feather.  O     Q 


OP6 


(D  o  'Q 

0       (^As 


PeO 


V 


The  reason  why  some  feathers,  like  ^iQ 

the  contour  feathers,  are  short  is 
because    growth    quickly    ceases. 

The  feathers  of  the  hackle,  saddle,  ^^^  c.-nia^ram  of  arrangement  of  the  tail  feathers, 
and   tail  of    the    male  are    long    be-      ^i-^lj,  feathers  of  right  anterior  row;  .4'i-^ '5,  feathers 
,1  ,1  •     J  •      •      it,  of  left  anterior  row;  .1/1- .1/7  and  .I/'i-.V't,  feathers  of 

cause  the  growth  period  is  in  them  Hght  and  lell  middle  rows;  /',-nand  PV/'e.  feathers 
prolonged.  The  sickle  feathers  of  of  right  and  left  posterior  rows  ;  o.  g-.,  oil  gland; 
,1        T        -u  i.-ii  •         r  /)- K,  dorso-ventral  line ;/?,  right :  i,  left. 

the  Leghorn  are  still  growing  for 

three  months  after  the  molting  period  ;  consequently  they  attain  a  length  of 
300  to  400  mm.  If  the  period  of  drying  up  of  the  growth  sheath  at  the 
base  of  the  sickle  feathers  could  be  delayed  in  the  Leghorn  for  an  entire 
year  they  would  become  each  a  meter  long.  The  reason  for  the  great  length 
of  the  tail  feathers  of  the  Tosa  fowl  is  that  they  do  not  cease  growing.  In 
this  respect  they  resemble  the  long  hair  of  Angora  guinea  pigs,  rabbits  and 
cats,  and  the  head  hair  of  man. 

Morphology  of  the  tail.  As  just  intimated,  only  certain  feathers  of  the  tail 
of  the  Tosa  fowl  grow  indefinitely.  It  is  now  necessary  to  describe  the 
structure  of  the  tail.     The  feathers  have  the  following  arrangement : 

The  posterior  row  {P)  consists  of  broad  feathers  with  rounded  ends  and 
constitutes  the  characteristic  "  fan  "  of  the  tail.  The  middle  row  (J/)  con- 
tributes the  characteristic  long  growing  feathers,  those  nearest  the  median 


46  INIIERITANCK    IN    POULTRY. 

line  being  longest.  The  sickle  feathers  (5)  may  belong  to  either  row,  so 
far  as  the  adult  position  indicates ;  but,  as  growing  feathers,  they  belong 
physiologically  to  the  middle  series.  The  anterior  row  (A)  is,  at  the  same 
time,  the  posterior  row  of  tail  coverts.  The  lateral  feathers  of  this  row  are 
the  smallest,  owing  to  a  late  and  brief  growth.  The  long  tail  of  the  Tosa 
fowl  is  thus  produced  by  the  prolonged  growth  period  of  the  middle  row  of 
feathers  including  the  sickle,  together  with  the  more  median  feather  of  the 
anterior  row. 

Cause  of  excessive  growth  of  tail ;  Cuiuiinghanf  s  experiments.  The  cause 
of  this  prolonged  growth  of  the  median  and  sickle  feathers  is  the  crucial 
point.  The  latest  student  of  the  subject,  Cunningham  (1903,  p.  232), 
quotes  Mr.  John  Sparks  as  stating  :   "In  order  to  ensure  very  great  length 

of  tail,  the  cocks  ought  to  be  kept  on  a  perch and  the  tail-feathers 

should  be  pulled  gently  every  morning."     Cunningham  adds:  "My  own 

e:cperiments tend  to  show  that  this  mechanical  treatment  of  the 

feathers  is  the  whole  secret  of  the  mystery. ' '  He  describes  in  great  detail 
how  he  stroked  the  tail  of  one  of  tv/o  cocks  daily  ;  the  other  not  at  all. 
When  a  feather  otopped  growing  he  pulled  it  out.     He  concludes  (p.  248)  : 

la  the  cock  whose  feathers  were  stimulated  by  pulling,  growth  did  not  go  on  at  a 
more  rapid  rate,  but  continued  for  a  longer  time  and  produced  a  longer  feather.  Thus 
in  cock  A  [not  stroked]  no  growth  took  place  after  April  i,  and  the  maximum  length 
was  2  feet  4)^  inches;  while  in  cock  B  [stroked]  growth  continued  till  July  13,  and  the 
maximum  length  was  2  feet  9^  inches. 

Half  a  page  farther  on  Cunningham  sums  up  thus  : 

The  long-tailed  cock  in  its  perfection,  therefore,  is  neither  a  sport  nor  a  breed,  but 
the  product  of  artificial  cultivation  ;  and  the  excessive  growth  of  the  feathers  is  the  result 
of  stimulation  applied  to  the  individual.  The  more  important  part  of  the  stimulation  is 
not  the  mere  pulling  of  the  feathers,  but  the  extraction  of  it  which  causes  the  growth  of 
its  successor. 


One  can  not  but  remark  that  Cunningham  here  contradicts  himself.  After 
having  laboriously  pulled  the  feathers  for  over  a  year  and  found  that  the 
feathers  are  stimulated  b^'  pulling,  he  states  :  "  The  most  important  part  of 
the  stimulation  is  not  the  pulling  but  the  extraction  of  the  feather  causing 
the  growth  of  its  successor."  Does  Cunningham  indeed  think  that,  origi- 
nally, by  extraction  of  a  feather  its  follicle  was  so  stimulated  that  it  there- 
after produced  feathers  which  neither  ceased  to  grow  nor  molted  and, 
moreover,  so  affected  the  germ  plasm  as  to  produce  a  race  with  a  tendenc}' 
toward  excessive  growth  of  feathers  ?  Certainly  such  a  conclusion  seems 
past  belief. 

Author's  experiments.  To  see  what  influence,  if  any,  stroking  the  tail 
feathers  has  upon  their  growth,  I  experimented  upon  two  cocks.  One 
(No.  3,  "Admiral  Togo")  was  stroked  twice  daily  by  passing  the  feathers 
of  the  middle  and  anterior  row  between  the  thumb  and  forefinger.     The 


TOSA    FOWL   AND    WHITE    COCHIN. 


47 


other  (No.  7,  "  General  Oyama  ")  did  uot  have  its  tail  stroked.  The  two 
birds  were  treated  similarly,  except  that  Admiral  Togo  was  confined  to  his 
perch  during  all  but  about  two  to  six  hours  per  day,  while  General  Oyama 
had  free  run  with  the  hens.  The  experiment  was  begun  July  20,  1904, 
when  the  cocks  were  103  days  old,  and  was  continued  until  March,  1905, 
when  "  Oyama  "  died  of  roup. 

The  relative  growth  of  the  corresponding  feathers  of  the  two  males  is 
shown  in  a  series  of  curves  (text  figure  D).     The  full  line  is  the  curve  of 


600 
500 
4-00 
300 

aoo 

100 
0 

600 
500 
400 
300 
200 
ICO 
0 


^  Aug.  Sept.  Oct.    Nov.     Dec.    Jan, ^        ,  Aug.  Sept.  Oct.  ^  Nov.  ^  Dec.  Jan. 

y. 

cl 

/' 

,^ 

N/i| 

"A 

yy 

^3 

5 

y 

'  y 

y 

y 

k^'^' 

y 

0 

/    / 

/""*"' 

7 

• 

• 

/ 

3 

7 

/ 

1/ 

• 

/ 

/ 

-^ 

7- 

,./ 

/^ 

■^ 

3 

/ 

y 

,7 

y 

y 

M^ 

/ 

^^ 

f 

1 
1 

/ 

y- 

/ 



7 

^ 

y\ 

r 

y 

x- 

3^ 

/ 

^^' 

1 

\7   ■ 

1 
1 

Fig.  D.— Curves  of  growth  of  certain  tail  feathers  of  Togo  (No.  3,  full  line)  and  Oyama  (No.  7,  dotted 
line).  Ml,  first  right  middle  tail  feather;  M.^,  M'j,  second  right  and  left  middle  tail  feathers;  Ms, 
third  right  tail  feather  ;  S,  right  sickle. 

the  stroked  feather  ;  the  dotted  line  that  of  the  unstroked.  These  curves 
show  several  things. 

First,  the  average  rate  of  growth  of  one  of  the  tail  feathers  in  the  Tosa 
fowl  is  about  3  mm.  per  day,  or  an  inch  a  week.  Consequently,  if  growth 
is  uninterrupted  and  the  feather  does  not  break,  it  should  come  to  be  over  a 
meter  long  by  the  end  of  one  year.  The  extremely  long  feathers — 5  meters 
or  more — on  record  are  acquired  by  (a)  rapid  growth,  ((5)  continuous  growth, 
(c)  preservation  of  the  tail  from  breakage,  and  {d)  long  life  of  the  individual. 
If  stroking  has  any  effect  it  must  be  by  altering  one  or  more  of  these  elements. 

Second,  the  curves  show  fluctuations  in  the  rate  of  growth  due  to  fluctua- 
tions in  the  condition  of  the  fowl. 

Third,  in  the  case  of  those  feathers  that  were  studied  during  the  greatest 


48  INIIKRITANCE    IN    POULTRY. 

period,  viz,  M,,  M.,,  M'.^,  the  stroked  feather  grew  more  rapidly  thau  the 
corresponding  unstroked. 

Fourth,  the  unstroked  feathers  of  No.  7  ceased  growing  earlier  than  the 
corresponding  stroked  feathers  of  No.  3. 

Whether  the  third  and  fourth  items  are  due  to  differences  in  treatment 
or  to  other  peculiarities  of  the  fowl  can  not  be  asserted  definitely.  In  any 
case  the  feathers  all  eventually,  at  about  six  months,  ceased  to  grow. 
Owing  to  the  death  of  No.  7  soon  after,  the  comparison  had  to  be  abandoned. 
The  result  agrees  with  Cunningham's  in  that  stroking  prolongs  the  period 
of  growth  ;  but  the  result,  depending  on  three  feathers,  can  hardly  be 
generalized.  It  would  not  be  surprising,  in  view  of  what  we  know  of 
functional  hypertrophy,  if  it  were  some  day  demonstrated  that  stroking 
always  prolongs  the  growing  period  of  a  feather.  This  is,  however,  an 
entirely  different  matter  from  proving  that  the  origin  of  the  long-tailed  con- 
dition of  the  Tosa  fowl  was  due  to,  and  its  maintenance  in  some  way  depends 
upon,  stroking. 

A  few  further  cxpeiiuiencs  have  been  made  with  Admiral  Togo  (fig.  31). 
I  have  found,  in  confirmation  of  Cunningham,  that  if  a  feather  that  has 
ceased  to  grow  be  forcibly  removed  it  is  quickly  replaced  by  another  that 
continues  to  grow.  Thus  a  feather  pulled  out  January  i,  1905,  had  grown 
steadily  to  November  i  ;  but  as  the  bird  was  needed  for  breeding  and  could 
not  be  confined,  the  tail  has  repeatedly  broken  off.  In  September,  1905,  it 
measured  over  900  mm. 

As  a  further  criterion  of  the  value  of  manipulation  in  causing  this  great 
growth  of  the  tail  feathers  of  the  Tosa  fowl,  it  becomes  important  to  see 
bow  this  physiological  characteristic  is  inherited  when  crossed  with  a  short- 
tailed  individual.     This  consideration  led  to  the  present  series  of  experiments. 

The  tail  of  the  Cochin  fowl  is  the  shortest  of  all  races  of  poultry.  Thus 
Wright  (1902,  p.  245)  expresses  the  ideal  of  the  fancier  :  "  The  tail  of  the 
cock  should  be  as  short as  possible." 

3.  Foot  F'eathering. — While  the  Cochin  is  very  heavily  feathered  on  the 
foot,  the  Tosa  fowl  is  typically  clean-legged.  However,  No.  3,  which  is 
not  the  father  of  any  of  my  hybrids,  shows  a  few  bunches  of  rudimentary 
feathers  or  hairs  on  the  tarsus. 

4.  Foot  Color. — The  willow  foot  of  the  Tosa  fowl  is  derived  directly 
from  the  Jungle  fowl.  The  white  foot  of  the  White  Cochin  seems  to  be  an 
albinic  form  of  the  yellow  foot  derived  from  its  Indian-Malay  ancestry. 

MATERIAL. 

First  Generation. — The  mother  was  a  White  Cochin  Bantam,  No.  35a 
(fig.  32),  of  unknown  origin,  but  apparently  pure  in  respect  to  the  four 
characteristics  here  under  consideration.  The  father  was  imported  from 
Japan,  having  been  purchased  in  New  York  city,  January,  1904.  It  has  a 
dark  Game  coloration  (fig.  29). 


TOSA    FOWL  AND   WHITE   COCHIN. 


49 


Second  Generation. — Two  hybrid  cocks,  Nos.  53  (fig.  34)  and  95  (fig. 
35),  were  successively  bred  to  their  sisters,  Nos,  58  cfig.  33),  94,  96,  and  98. 

RESULTS. 

I.  General  Plumage  Color. — First  hybrid  generation.  Of  7  offspring, 
3  cocks  and  3  hens  developed  their  adult  plumage.  The  males  were  all  of  the 
male  Tosa-fowl  coloration  except  that  every  feather  was  repeatedly  barred 
with  white  (figs,  34,  35,  37A).  The  females  were  all  of  the  female  Tosa-fowl 
coloration  except  that  the  shafting  was  much  broadened  (fig.  37)  ;  also  the 
saddle  feathers  and  the  proximal  secondaries  were  obscurely  barred  black- 
and-buff. 

Second  hybrid  generation.  Among  57  individuals  we  have  the  following 
distribution  of  plumage  color  : 


Color. 

No. 

Per  cent. 

White 

16 

41 

28.1 
71.9 

Pigmented 

The  original  white  color  has  reappeared  in  about  one-fourth  of  the  cases 
(fig.  38)  ;  plumage  color  segregates  in  the  germ  cells  of  the  first  hybrid 
generation  in  true  Mendelian  fashion.  Of  the  16  whites,  only  5  were  without 
trace  of  reddish  pigment.  Such  pigment  occurred  on  the  breast,  top  of 
head,  and  remiges.  The  purity  of  the  germ  cells  from  which  these  whites 
sprang — the  completeness  of  segregation — is  not  always  perfect. 

The  41  pigmented  individuals  show  a  curiously  mixed  lot  of  coloration. 
Of  14  vsx2X\xxQ.  females,  6  are  like  the  female  Tosa  fowl,  without  barring,  but 
sometimes  with  wider  shafting  than  male  Tosa  fowl.  The  remainder  have 
feathers  of  the  back  and  wing  coverts  barred  with  lighter,  even  with  white — 
a  condition  not  found  in  the  female  first  hybrids.  One  of  these  (No.  659) 
shows  a  mixture  of  female  Tosa  and  female  Partridge  Cochin  coloration.  As 
no  Partridge  Cochin  is  involved  in  the  immediate  ancestry,  this  looks  like  a 
* '  reversion  ; ' '  the  characteristic  has  probably  lain  latent  in  the  White 
Cochin.  Of  10  males,  two  show  no  trace  of  white,  and  may,  consequently, 
be  considered  as  homozygous.  The  remainder  are  more  or  less  barred  with 
white.  One  bird  (No.  646)  shows  a  remarkable  mixture  of  Tosa  and  male 
Partridge  Cochin  coloration. 

2.  Tail  Length. — First  hybrid  generation.  All  the  three  males  reared 
developed  abnormally  long  middle  tail  feathers.  One  of  these  birds  died 
young.  The  second  bird  (No.  53,  fig.  34)  lived  to  be  exactly  one  year  old. 
Its  sickles  were  427  mm.  long  and  had  stopped  growing.  It  had  suffered  a 
severe  paralytic  stroke  four  months  before  its  death.  The  remaining  cock 
(No.  95,  fig.  35)  had  a.t  iij4  months  sickle  feathers  360  mm.  long  and  still 
growing.  These  feathers  had  thus  grown  at  a  rate  of  about  i  mm.  a  day,  or 
4 


50 


INHERITANCE   IN   POULTRY. 


ouly  one-third  that  of  its  father.     The  long-tailed  characteristic  of  the  male 
has  been  inherited,  but  in  a  reduced  form. 
Second  hybrid  generation.  Still  immature. 

3.  Foot  Feathering. — First  hybrid  generation.  Of  the  7  individuals  all 
have  the  feet  feathered  ("  booted  ")  and  the  females  are  provided  with  a 
"  vulture  hock."     The  feathering  is  usually  less  than  in  the  Cochin. 

Second  hybrid  generation.  Among  the  55  individuals  of  this  generation  all 
degrees  of  foot  feathering  were  obtained.  Eight  cases  are  recorded  as 
"  heavily  booted,"  27  as  "booted,"  13  as  slightly  booted,  and  7  as  non- 
booted.  The  classification  is  arbitrary  and  therefore  the  exact  proportions 
not  significant.  The  important  outcome  is  that  a  good  share  of  this  genera- 
tion is  essentially  clean-legged  like  the  Tosa-fowl  ancestor,  and  an  approxi- 
mately equal  proportion  is  heavily  booted  like  the  Cochin  ancestor,  while 
the  rest  are  feathered  to  an  intermediate  degree  like  the  parents. 

4.  Foot  Color. — This  has  a  curious  way  of  changing  during  the  early 
months  of  the  individual.  White  is  often  represented  in  the  young  by 
yellow.  A  ' '  slate  blue  "  or  "  bluish  black  ' '  occurs  ;  this  may  be  a  form  of 
the  willow  from  which  yellow  has  been  extracted. 

First  hybrid  generation.  Of  5  individuals  two  are  recorded  as  white,  one 
as  yellow,  one  as  willow,  and  one  as  slate  blue.  Here  is  practically  equal 
frequency  of  the  light  and  dark  types. 

Second  hybrid  generation.  Fifty-three  individuals  give  the  following  dis- 
tribution of  foot  color  : 


Color. 

/. 

Per  cent. 

White 

Yellow 

II 

16 

20 

6 

Willow 

Slate  or  bluish 

Total 

53 

100 

This  shows  a  practical  equivalence  of  light  and  dark  foot  colors  as  in  the 
first  generation.  The  interpretation  of  this  result  must  be  left  for  later 
studies. 

5.  Correlation  of  Characteristics. — Considering  only  the  three 
characteristics  of  plumage  color,  booting,  and  foot  color,  and  assuming  that 
game  color  and  boot  are  dominant  and  light  and  dark  feet  equally  apt  to 
occur,  we  find  the  following  calculated  and  actual  frequency  of  each  combi- 
nation (actual  percentage  is  in  italics)  : 


Game  plumage  . 
White  plumage.. 


,  To;*    69.Si- 


Booted 5C.3^    58.5';, 


Non-booted IS.TfS 

(Booted 18.75^ 
Non-booted 0.25$ 


ii.4^ 


Li^htfeet 28.1^ 

Dark  feet 23.15^ 

'Light  feet 9.4^ 

Dark  leet 9.' 


OS  ,^  f  Light  feet 9.45? 

■"*•*'"  I  Dark  feet 9.4^ 

,„y  J  Light  feet 3.1^ 

^•''>"  t  Dark  feet  S.ljf 


50.8^ 

t8.Si, 

5.7^ 

5.7i 

15. li. 

O.Oji 
1.9'^ 


DARK    BRAHMA    AND   TOSA    FOWI,.  "     51 

Consideriug  the  intrinsic  diificulties  of  classification  due  to  the  partial 
blending  of  characteristics,  there  is  a  fairly  close  correspondence  between  the 
calculated  and  the  actual.  This  result  prov^es  that  there  is  little  if  any 
necessary  correlation  between  the  characteristics  in  question  ;  they  may 
combine  in  a  chance  fashion  in  the  second  hybrid  generation. 

CONCLUSIONS. 

The  inheritance  of  color  in  this  cross  between  a  white  and  a  game-colored 
breed  is  remarkable  in  that  white  is  not  dominant — as  is  usually  the  case — 
nor  recessive  ;  but  inheritance  is  particulate  in  the  heterozygote,  producing 
barred  offspring.  Segregation  nevertheless  occurs  in  the  second  hybrid 
generation,  but  the  extracted  whites  and  game  colored  birds  are,  for  the 
most  part,  no  longer  as  pure  in  color  as  their  grandparents  were.  The 
germ  cells  are  no  longer  perfectly  pure — they  have  become  infected  by  con- 
tact with  the  opposite  quality. 

The  long-tailed  characteristic  behaves  in  inheritance  like  a  unit  character — 
in  no  wise  different  from  plumage  color.  One  can  not  help  doubting  whether 
it  originated  by  any  different  method  from  that  in  which  the  diverse  colors 
of  poultry  have  arisen. 

Foot  feathering  is  dominant  here  as  in  many  other  cases  ;  yet  the  domi- 
nance is  incomplete.  The  germ  cells  of  the  second  hybrid  generation  are 
no  longer  pure. 

The  White  Cochin  has  no  sexual  dimorphism  in  plumage  color,  while  the 
Tosa  fowl  is  strongly  dimorphic.  Every  one  of  the  first  hybrids  is  dimorphic 
in  plumage  coloration,  the  two  sexes  resembling,  except  for  the  white, 
respectively  the  female  and  the  male  Tosa  fowl  It  is  striking  to  see  how 
from  a  germ  cell  of  the  male  Tosa  fowl  either  a  bird  colored  like  a  male 
Tosa  or  a  bird  colored  like  a  female  Tosa  may  arise.  The  male  germ  cells 
contain  the  Aniagen  not  only  of  the  male  characteristic  but  also  of  the 
female  characteristic  (Darwin,  1876,  Chapter  XIII). 

Series  X.— Dark  Brahma  and  Tosa  Fowl. 

STATEMENT  OF  PROBLEM. 

This  series  was  undertaken  primarily  to  test  inheritance  of  secondary  sexual 
characteristics  and  the  possibilitj-  of  transferring  them  from  one  sex  to 
another. 

the;  races  as  a  whole. 

The  Dark  Brahma  male  and  female  have  been  described  at  page  32  ;  the 
Tosa  fowl,  male  and  female,  at  pages  43,  44.  Each  race  has  a  strongly 
marked  sexual  dimorphism  in  plumage  color.  The  males  have  feathers  of  a 
more  uniform  color  ;  the  female  Dark  Brahma  has  penciled  feathers  ;  the 
female  Tosa  fowl  has  mossy  feathers  with  prominent  light  shafting. 


52 


INHERITANCE   IN   POULTRY. 


TABLE  OF   CHARACTERISTICS. 


No. 


I 

2 

3 
4 
5 
6 

7 
8 

9 
lo 

II 

12 

13 


Tosa  fowl. 


Characteristic. 


I 


Female. 


vShafting 

Lacing  on  hackle. 
Lacing  elsewhere. 

Penciling 

Red  wing-bar.  .  . . 
White  wing  bow . 

Comb 

Earlobe 

Iris  color 

Foot  color 

Vulture  hock 

Foot  feathering.. . 
Tail  feathers  .  .    . 


Male. 


See 
page- 


Present  .  .  Absent.  . 
Present  .  . !  Present  . 
Absent. . .  Absent. . 
Ab.sent  . .  Absent. 
Absent. .  .  Present . 
Absent.  .  .    Absent. . 

Single 

While,  red  edge. 

Red 

Willow     

Absent 

Absent , 

Long 


32 
33 
33 
48 

48 
44-48 


Dark  Brahma. 


Female. 


Male. 


Absent . 
Present 
Absent. 
Present 
Absent. 
Absent. 

Pea 

Red  or  bay 

Yellow.    .  . 

Yellow .    . . 

Present  . . . 

Present  . . . 

Short 


Absent. 
Present 
Present 
Absent. 
Present 
Present 


See 
page- 


33 
33 
33 
34 
34 


REMARKS  ON  THE  CHARACTERISTICS. 

1 .  Sh.\fting. — In  plumage,  shafting  is  a  light  streak  on  the  shaft  and  adja- 
cent parts  of  the  vane.  Of  the  two  parental  races  it  occurs  only  in  the 
female  Tosa  fowl  (fig.  30).  The  light  shaft-stripe  is,  however,  widespread 
among  females  of  certain  dark  or  silvered  races — e.  g. ,  Silver  Wj'andotles, 
Silver-gray  and  Dark  Dorkings,  Silver  Duckwing  Games,  and  Silver  Penciled 
Hamburghs.  It  crops  out  in  many  individuals  where  its  occurrence  is  regarded 
by  the  "  fancy  "  as  a  "  defect."  It  is  an  original  characteristic  of  poultry 
introduced  from   Gallus  ba?ikiva,   whose   female  exhibits  it  conspicuously 

(fig-  39)- 

2.  Hackle  Lacing. — Among  most  broken- colored  poultr)'  the  hackle 
feathers  are  unlike  those  of  the  rest  of  the  plumage.  Usually  the  hackle  has 
a  dark  band  in  the  center  and  is  margined  or  laced  by  white — more  rarely  by 
yellow  or  red.  In  the  female  Jungle  fowl  (fig.  39)  the  feathers  of  nape  and 
hackle  hav^e  a  black  center  (with  broad,  straw-colored  shafting)  and  are  laced 
with  straw  color.  The  male  Jungle  fowl  has  hackle  feathers  of  a  solid  red 
color.  In  the  descent  of  the  domestic  poultry,  hackle  lacing  seems  to  have 
been  transferred  to  the  male  sex  also. 

3.  Body  Lacing. — Few  races  of  poultry  exhibit  lacing  elsewhere  than  on 
the  hackles.  It  is  very  prominent  on  the  Indian  female,  but  is  not  found  on  the 
Jungle  fowl  of  either  sex.  In  the  Dark  Brahma  male  (fig.  19)  it  occurs  only 
on  the  saddle  feathers.  Whether  its  laced  saddle  is  derived  from  the  Indian 
or  is  due  to  a  spreading,  through  correlation,  from  the  hackles  can  not  be 
said.  Lacing  is  found  on  the  breast  of  Game  fowl  and  over  much  of  the 
body  of  the  female  Dark  Dorking.  Among  certain  derived  races,  such  as 
the  Spangled  Polish  and  the  Laced  Wyandottes,  it  affects  nearly  the  whole 
plumage  and  is  ver}-  conspicuous. 


DARK    BRAHMA    AND   TOSA    FOWL.  53 

4.  PenciIvING. — This  may  be  defined  as  a  concentric  repetition  on  the 
feather  of  alternating  bands  of  the  lacing  and  the  ground  color.  In  the  hackle 
of  the  female  Jungle  fowl  the  straw  color  of  the  lacing  is  repeated  in  the  center, 
the  two  light  areas  being  separated  by  a  black  band.  In  the  female  Indian 
fowl  the  feathers  of  the  throat  are  laced,  but  lower  down  on  the  larger  back- 
feathers  and  on  the  wing  bows,  there  is  a  second  or  inner  lacing — /.  e. ,  the 
wing  is  penciled  ;  *  consequently  penciling  may  be  said  to  be  a  fundamental 
form  of  coloration  in  the  genus  Callus.  Penciling  occurs  widespread  among 
the  derived  or  secondary  races  of  poultry,  particularly  in  the  "  partridge  " 
varieties.  A  curious  modification  of  penciling  is  the  straight  transverse 
barring  of  the  feather  familiar  in  the  Barred  Plymouth  Rock  and  Penciled 
Hamburghs. 

5.  Red  Wing-Bar. — The  wing-bar  is  formed  by  the  lower  wing  coverts, 
usually  the  first  to  third  rows  above  the  remiges  or  flight  feathers.  In  the 
male  of  many  races  of  fowl  these  differ  from  the  more  proximal  rows.  In 
the  Dark  Brahma  male  they  have  white  and  red  in  addition  to  black.  The 
wing-bar  has  probably  been  derived  by  the  Dark  Brahma  male  from  the 
Indian  fowl.  In  the  male  Tosa  fowl  the  lower  wing  coverts  are  tipped  with 
red,  but  they  show  no  white. 

6.  White  Wing-Bows. — The  wing-bow  is  formed  by  the  upper  or  proximal 
rows  of  wing  coverts — /.  e.,  above  the  third.  These  coverts  are  frequently 
of  a  different  color  from  the  wing  bar.  They  are  red  in  the  male  Indian 
and  Malay,  but  they  are  white  f  in  the  male  Aseel.|  The  white  wing-bow 
of  the  Dark  Brahma  has  probably  been  derived  from  this  source.  The  wing- 
bow  of  the  male  Tosa  fowl,  like  that  of  the  Jungle  fowl  and  Games,  is  red. 

8.  White  Eari,obe  is  a  derived  color,  the  primitive  condition  being  red 

(page  33). 

9.  Iris  Color. — The  origin  of  the  yellow  eye  of  the  Brahma  has  been  dis- 
cussed at  page  33.  The  red  eye  of  the  Tosa  fowl  is  found  in  most  Games 
and  is  the  prevailing  color  among  domestic  poultry. 

MATERIAL. 

Mother. ~'^o.  121,  Dark  Brahma  Bantam  (fig.  18). §  She  is  a  beautifully 
penciled  bird,  with  horn-colored  beak,  pearl-colored  iris,  prominent  vulture 
hocks,  and  booted  down  to  the  outer  two  toes.  To  test  her  purity,  she  was 
bred  for  a  month  to  No.  122,  Dark  Brahma  male,  also  from  Mr.  Hodges. 
Their  offspring  died  before  hatching  except  one  (No.  146  ^),  which  is  a 
typical  Dark  Brahma. 

*CompareWriglit,  1 902.  p.  334,  and  American  Standard  of  Perfection,  1905,  p.  207,  figure. 

t  According  to  Ludlow's  painting  in  Wright,  1902,  opposite  p.  326. 

X  Since  the  above  was  written  I  have  purchased  a  male  Aseel  which  has  dark  coverts 
tipped  with  white. 

§  Weight  1,300  grams,  received  February,  1905,  from  Mr.  F.  H.  Hodges  Red  Bank, 
New  Jersey,  marked  F.  H.  H.,  No.  66,  also  No.  338. 


54  INHERITANCE    IN    POULTRY. 

Father. — A  Tosa  fowl  bred  at  the  station,  No.  8a,  "General  Oyama," 
referred  to  at  page  46. 

RESULTS. 

The  produce  was  5  females  and  16  males  (fig.  40).  They  are  all  blocky 
birds,  verj-  different  from  the  Tosa  fowl,  but  longer  than  the  Brahma.  The 
maternal  or  Brahma  type  is,  however,  predominant.  Only  the  first  genera- 
tion of  hybrids  has  been  reared. 

1.  Shafting. — The  male  hybrids  are  mostly  without  shafting  on  the  feath- 
ers of  the  back  and  the  wing  coverts.  Two,  however,  show  clear  yellow 
shafting  on  these  feathers,  and  in  two  others  the  shafting  is  a  light  buff 
color.  The  female  hybrids  have  these  feathers  shafted.  Shafting  is  domi- 
nant in  the  female  hybrids.     It  is  doubtfully  transferred  to  some  males. 

2.  Hackle  Lacing. — This  showed  on  all  hybrids  of  both  sexes. 

3.  Body  Lacing. — In  the  male  hybrids  the  saddle  feathers  and  sometimes 
the  tail  coverts  are  laced  with  vellow  as  in  the  Brahma.  Such  lacing  does 
not  appear  on  the  female.     Lacing  in  the  male  sex  appears  to  be  dominant. 

4.  Penciling. — This  appears  as  typical  penciling  or  as  barring  on  the  back 
and  saddle  and  on  the  exposed  parts  of  the  secondaries  of  the  female  hybrids. 
It  does  not  appear  on  the  males.  Penciling  seems  to  be  dominant  over 
mossiness  and  to  be  confined  to  the  female  sex. 

5.  Red  Wing-Bar. — This  is  present  in  all  of  the  first  hybrid  males,  but  the 
red  is  deeper  and  spreads  farther  over  each  feather  than  in  the  Dark  Brahma, 
the  red  of  the  Tosa  fowl  having  its  effect.  The  female  is  without  wing-bar 
as  in  the  female  parents. 

6.  White  Wing-Bow. — Of  13  hybrid  males  four  show  no  white  in  the 
upper  wing  coverts  (fig.  40) ;  but  one  of  these  has  a  light  buff  bow — a  tendency 
toward  white.  The  others  have  a  small  amount  of  white,  which  is  derived 
from  the  Dark  Brahma.  The  white  has,  however,  been  clearly  reduced  in 
amount.     The  interpretation  of  this  result  must  await  further  breeding. 

7.  Comb. — In  every  hj^brid  the  comb  is  pea,  proving  the  dominance  of  that 
form  over  the  single.  The  pea  is,  however,  often  atypical,  the  lateral  ridges 
being  rudimentary.     Dominance  is  not  always  perfect. 

8.  Earlobe  Color. — Every  hybrid  shows  some  white,  as  in  the  Tosa  fowl  ; 
but  this  white  tends  toward  yellow — a  much  diluted  red.  White  seems  to 
dominate,  but,  if  so,  the  dominance  is  imperfect. 

9.  Iris  Color. — This  is  red  in  the  hybrids;  but  in  two  cases  the  red  ap- 
proaches orange.  The  iris  color  of  the  Tosa  fowl  is  dominant,  but  imper- 
fectly so. 

10.  Foot  Color. — Of  21  hybrids,  all  males  (16)  show  yellow  feet  and  all 
females  (5)  willow  feet.     This  dimorphism  is  not  found  in  the  parent  races. 

1 1 .  Vulture  Hock. — The  hybrids  show  a  tendenc}^  toward  long  feathers 
hanging  over  the  heel  (fig.  40).  In  one  case  these  had  reached  a  length  of 
105  mm.  by  six  months  ;  in  another,  about  90  mm.     In  other  cases  these 


FRIZZLE    AND    SILKY.  55 

feathers  are  much  reduced  from  the  Brahma  type,  and  in  one  or  two  cases  it 
is  doubtful  if  they  are  present.  We  have  to  do  here  either  with  a  blending 
characteristic  or  else  a  very  imperfect  dominance  of  the  vulture  hock. 

12.  Foot  Feathering. — This  is  always  present  in  the  hybrids,  but  is 
usually  less  heavy  than  in  the  Dark  Brahma  (fig.  40).  Booting  is  dominant, 
but  is  imperfectly  so. 

13.  Tail  Feathers. — 'As  none  of  the  hybrids  are  over  six  months  old,  it 
is  impossible  to  report  fully  on  the  inheritance  of  this  characteristic.  While 
in  some  male  hybrids  the  tail  feathers  already  surpass  in  length  the  middle 
tail  feathers  of  the  adult  Brahma  parent  and  are  still  growing,  in  no  ca.se 
have  they  made  the  extraordinary  growth  of  the  Tosa  fowl. 

CONCLUSIONS. 

Method  of  Inheritance. — The  color  characteristic  of  shafting  and 
penciling  in  the  female,  and  body  lacing,  red  wing  bar,  and  white  wing  bow 
in  the  male,  appear  to  dominate  in  the  respective  sexes ;  but  dominance,  if 
such  it  is,  is  alwa3'S  imperfect,  in  that  traces  of  the  opposite  allelomorph  are 
sometimes  found.     Furthermore  : 

Red  eye  color  dominates  over  yellow  (not  always  perfectly). 

Booting  is  dominant  over  clean  leg. 

Earlobe  color  is  something  of  a  mixture. 

Vulture  hock  is  sometimes  very  imperfectly  "  dominant." 

The  length  of  tail  feathers  is  perhaps  a  blend. 
Sex  in  Inheritance. — For  the  most  part  a  sexually  dimorphic  charac- 
teristic is  inherited  only  by  the  proper  sex.  In  the  hybrids  of  this  series, 
however,  shafting  seems  to  have  been  partially  transferred  from  the  female 
to  some  males.  Most  peculiar  is  the  inheritance  of  foot  color,  where  all  the 
female  hybrids  show  the  willow  foot  of  their  father,  and  all  male  hybrids 
the  yellow  foot  of  their  mother. 

Series  XI.— Frizzle  and  Silky. 

STATEMENT  OF  PROBLEM. 

This  series  of  crossings  was  made  to  learn  the  inheritance  of  the  allelo- 
morphs given  below. 

THE  RACES  AS  A  WHOLE. 

The  origin  of  the  Frizzle  fowl  (figs.  41  and  42)  is  not  definitely  known. 
Darwin  (1876,  Chapter  VII)  states  that  they  are  not  uncommon  in  India, 
and  Temminck  states  that  they  are  domesticated  also  in  Java,  Sumatra,  and 
all  the  Philippine  Islands,  being  prevailingly  white.  They  must  have  been 
brought  to  Europe  early,  since  they  are  described  by  Aldrovandus  in  1645 
from  a  specimen  sent  him  from  Parma.  Willoughby,  in  his  Ornithology 
(1676),  says  that  he  had  seen  them  in  England.  The  recurving  of  feathers 
is  found  in  many  species  of  birds.  It  usually  occurs  on  the  neck,  where  it 
forms  a  ruff  ;  more  rarely  over  the  entire  body.     Frizzled  canary  birds  are 


56  INHERITANCE    IN    POUETRY. 

occasioually  exhibited.  Frizzling  is  probablj'  morphologically  related  to 
"  rough  coat  "  iu  mammals.     The  frizzled  characteristic  is  a  typical  sport. 

The  Silky  fowl  (fig.  43)  is  likewise  of  great  antiquity.  Marco  Polo  saw 
it  in  Asia  in  the  thirteenth  century  (teste,  Diirigen,  1886,  p.  298).  Gesner 
described  it  in  1555.  It  is  a  native  of  eastern  India,  coming,  according  to 
Blyth  (Tegetmeier,  1867,  p.  221),  from  China,  Malacca,  and  Singapore.  A 
condition  allied  to  silkiness  (described  below  at  page  57)  is  found  in  other 
races  of  poultry,  particularly,  as  the  following  statements  show,  iu  the 
Cochins. 

Tegetmeier  (1867,  p.  46)  says  : 

The  singular  variety  known  as  Silky  Cochins,  or  sometimes  as  Emu  fowls,  is  simply 
an  accidental  variation  of  plumage  which  occasionally  occurs  and  which  may  be  perpetu- 
ated by  careful  breeding.  The  cause  of  the  coarse  fluffy  appearance  of  these  remarkable 
fowls  is  to  be  discovered  in  the  fact  that  the  barbs  of  the  feathers  instead  of  being  held 
together  by  a  series  of  hooked  barbules  (so  as  to  constitute  a  plane  surface,  as  occurs  in 
all  ordinary  feathers)  are  perfectly  distinct,  and  this  occasions  the  loose  fibrous  silky 
appearance  from  which  the  fowl  obtains  its  name. 

An  engraving  of  such  a  feather  is  given  by  that  author  at  page  224. 

Wright  (1902,  p.  255)  states  that  he  has  seen  no  Emu  fowl  "  now^  for 
twenty  years,"  and  makes  the  suggestion  that  this  entire  "silkiness"  of 
feather  is  the  extreme  limit,  perhaps,  of  the  kind  of  plumage  which  gives 
fluffiness  to  the  leg  region  of  American  Buff  Cochins. 

The  fluff  of  Cochins  and  Brahmas  has  indeed  many  points  of  similarity  in 
structure  with  the  feathers  of  the  Silky.  In  one  feather  from  the  abdomen 
of  a  Brahma  hen,  whose  shaft  is  35  mm.  long,  I  find  the  barbs  very  long  (up 
to  30  mm.)  and  not  connected  together.  Each  barb  bears,  proximally,  two 
rows  of  short,  flat,  hook-shaped  barbules  alike  on  the  two  sides.  Beyond, 
there  are  a  few  short  barbules  that  taper  to  a  hair-like  apex.  Still  more 
distall}'  on  the  barb  the  barbules  may  attain  a  length  of  5  mm. ,  be  altogether 
devoid  of  booklets,  but  show  a  segmented  condition  as  in  the  Silky  Far 
from  my  preconceived  notion,  I  find  few  intergrades  between  the  short  barb- 
ules and  the  others.  The  more  proximal  of  the  long  barbules  are  the  longest 
of  all,  and  the  short  barbules  (which  rarely  exceed  0.5  mm.  in  length)  also 
occur  here  scattered  among  the  long  ones.  There  thus  seems  to  be  a  dis- 
continuity between  the  two  kinds  of  barbules,  and  this  harmonizes  with  the 
view  that  the  long  barbule  is  a  mutational  form  of  the  more  typical  short 
barb  tile. 

As  to  the  relation  of  the  plumage  of  the  Silky  fowl  to  the  fluff  of  Cochins, 
I  have  formulated  the  following  hypothesis :  Long  and  short  barbules  are 
two  dimorphic  forms  found  among  birds.  This  dimorphism  has  been  recog- 
nized in  the  terminology  "down  feathers"  and  "contour"  +  "quill" 
feathers.  Down  feathers  may  or  may  not  have  a  shaft  ;  they  have  barbs, 
and  usually  barbules,  the  latter  being  long  and  devoid  of  cilia  or  booklets. 
In  the  contour  and  quill  feathers  of  most  birds  the  short  barbules  alone  are 


FRIZZLE   AND   SILKY. 


57 


present.  But  in  some  birds  the  barbules  are  long  and  devoid  of  cilia  or  hook- 
lets  as  in  the  Ratitae  (ostrich,  emu,  cassowary,  etc.).  In  poultry  the  down 
feathers  are  characterized  by  absence  of  booklets,  and  the  ventral  abdominal 
feathers  of  poultry  belong  to  this  category.  In  the  Silky  fowl  the  contour 
feathers,  in  the  strict  sense,  are  absent,  or  rather  they  have  gained  long 
bookless  barbs,  and  consequently  liave  become  in  so  far  down  feathers. 
But  the  feathers  of  the  Silky  fowl  have  one  new  characteristic  not  found  in 
any  other  long-barbed  forms,  namely,  the  bifurcation  and  anastomosis  of 
the  barbs  (page  58). 

TABLE  OF   CHARACTERISTICS. 


No. 

Characteristic. 

Frizzle  fowl  (Game). 

Silky  fowl. 

I 
2 

3 
4 
5 
6 

7 
8 

Plumage  color 

Comb  form 

Shaft  of  contour  feather. 

Barb  length 

Barb  form 

Number  of  toes 

Skin  color 

Dark,  black,  red,  and  buff. 

Rose 

Recurved 

Short 

Twisted  about  long  axis.  .  . 

Four 

White   

White. 

Single. 

Straight. 

Long. 

Straight. 

Five  or  six. 

Black. 

Present. 

Crest 

Absent 

REMARKS  ON  THE  CHARACTERISTICS. 

1 .  Plumage  Color. — This  characteristic  is  very  variable  in  Frizzles,  owing 
to  the  fact  that  fanciers  have  established  no  color  "  varieties,"  although  an 
effort  is  now  being  made  in  that  direction.*  As  stated  below  in  detail,  my 
Frizzles  were  of  varied  and  mixed  colors. 

2.  Comb  Forms. — The  "American  Standard  "  calls  for  single  comb  in  the 
Frizzle  and  rose,  or  rather  strawberry,  comb  in  the  Silkies.  My  Frizzles 
have,  on  the  contrary,  a  rose  comb,  and  my  Silkies  either  a  .single  comb  or  a 
rose  comb,  the  Silky  being  impure  in  respect  to  this  characteristic. 

3-5.  Feather  Form. — In  the  Frizzles  the  contour  feathers  have  the  shaft 
curved  so  that  its  outer  surface  becomes  concave.  This  is  most  striking  in 
the  neck  region,  where  a  ruff  is  formed  (fig.  41).  The  wing  primaries  are 
modified  in  another  direction,  since  in  them  the  barbs,  in  groups  of  4  to  8. 
are  twisted  in  corkscrew  fashion  about  their  own  axis  and  through  180°  or 
more  ;  consequently  the  gray  surface,  which  is  normall)-  next  the  body, 
comes  to  lie  outermost.  Such  a  twisting  of  the  barbs  sometimes  occurs  in 
primaries  of  non-frizzled  races  ;  particulary  I  have  found  it  in  the  eighth 
primary  of  some  Houdans.  The  barbs  of  the  remiges  of  the  Frizzles  are 
mostly  .short,  and  in  some  cases  are  lacking  altogether,  being  easih'  broken  off. 

The  feathers  of  the  Silky  fowl  are  remarkable  in  all  parts  of  the  plumage. 
The  contour  feathers,  as  already  stated,  are  down  feathers,  whose  shaft  is 


*The  new  "American  Standard  of  Perfection,"  published  by  the  American  Poultry 
Association,  1905,  p.  248,  directs  that  color  should  be  "  solid — black,  white,  red,  and  bay 
admissible,  provided  the  birds  match  when  shown  in  pairs,  trios,  and  pens." 


58  INHERITANCE   IN   POULTRY. 

usually  delicate  but  not  othenvise  atypical.  The  barbs  are,  on  the  other 
hand,  remarkably  long.  Thus  in  a  contour  feather,  from  the  middle  of  the 
dorsal  region,  whose  shaft  is  25  mm.  long,  the  prevailing  length  of  barb  is 
35  to  45  mm.  The  barbs  are,  moreover,  remarkable  in  that  they  frequently 
bifurcate,  even  repeatedly.  In  a  feather  before  me,  one  barb,  taken  at 
random,  undergoes  bifurcation  four  times.  As  the  branches  are  not  all  in 
one  plane,  the  feather  becomes  exceedingly  fluffy.  At  the  proximal  end  of 
the  shaft  the  barbs  arise  parallel  and  produce  an  imperfect  web  close  to  the 
shaft,  but  marginally  the  web  is  lost.  Distally  on  the  shaft  the  barbs  arise 
more  irregularly  from  the  shaft,  often  bifurcating  almost  immediately,  so 
that  no  web  or  vane  is  formed.     The  barbs  may  also  anastomose. 

The  barbules  are  not  less  strikingly  modified  than  the  barbs.  They  attain 
a  length  of  from  i  to  2  mm.  Moreover,  it  is  not  possible  here,  as  in  other 
races,  to  distinguish  between  a  distal  series  of  barbules  carrying  a  row  of 
booklets  or  cilia  and  a  proximal  series  without  booklets  but  with  a  folded 
edge  into  which  the  booklets  of  the  distal  barbules  catch.  This  impossibility 
is  due,  first,  to  the  fact  that  the  barbules  are  not  in  two  series  merely,  but  may 
arise  in  three  planes,  or  irregularly  ;  also,  morphologically,  all  the  barbules 
on  the  barb  are  alike.  They  are  all  segmented  like  the  ordinary  distal  barbule, 
and  the  booklets  are  represented  by  minute  thickenings  at  the  end  of  each 
segment.  As  a  consequence  of  this  structure  the  barbs  do  not  hang  together 
to  form  a  vane  and  the  fluffiness  is  still  further  exaggerated. 

The  quill  feathers  of  the  wing  (remiges)  and  tail  (rectrices)  of  the  Silky 
are  modified,  but  to  a  less  degree.  Primaries,  secondaries,  and  coverts  are 
all  affected.  The  proximal  part  of  the  vane  is  nearly  normal  ;  the  distal  part 
has  barbs  of  t\vice  to  thrice  the  normal  length.  The  barbs  may  bifurcate 
repeatedly  and  even  anastomose  in  the  plane  of  the  vane.  The  barbules  also 
are  modified,  being  much  shortened.  Proximal  as  well  as  distal  barbules 
may  carry  booklets,  as  is  seen  in  the  middle  part  of  the  feather.  In  the 
proximal  part  of  the  feather,  on  the  other  hand,  the  proximal  barbules  are 
without  booklets.  The  feathers  of  the  tail  have  the  web  even  more  broken 
up  than  those  of  the  wing. 

The  silky  condition  of  the  feather  is  a  characteristic  that  is  either  entirely 
new  (progressive  in  de  Vries's  sense)  or  possibly  latent  (in  de  Vries's  sense) 
in  typical  fowl,  so  that  its  appearance  in  the  Silky  is  a  case  of  ' '  degression  ' ' 
(de  Vries).  If  the  former,  we  should  expect,  according  to  de  Vries,  the 
offspring  between  a  Silky  and  a  non-Silky  to  show  a  mosaic  of  the  parental 
feather  characteristics  and  a  non-Mendelian  inheritance  of  silkiness  ;  if  the 
latter,  a  recessiveness  of  the  varietal  characteristic  of  silkiness  and  its  Men- 
delian  inheritance.* 


*  De  Vries,  1905,  p.  280  :  "  The  character  of  the  species  is  dominaut  iu  the  hybrid,  while 
that  of  the  variety  is  recessive."  On  the  latter  of  the  two  assumptions  made  above,  plain 
plumage  is  the  species  character  ;  silky  plumage,  the  varietal. 


FRIZZLE    AND    SILKY.  59 

6.  Number  of  Toes. — This  is  constantl}'  four  in  pure-bred  Frizzles.  In 
Silkies  a  fifth  toe  is  always  present.  The  extra  toe  frequently  has  a  double 
nail,  or  the  division  may  be  complete,  resulting  in  six  toes. 

7.  Skin  Color.— In  the  case  of  the  Frizzle  the  skin  is  white,  sometimes 
tinged  with  yellow  pigment.  The  skin  of  the  Silky  is  notoriously  blue-black. 
This  is  a  clear  case  of  melanism,  and  since  early  times  has  been  associated 
with  the  other  peculiarities  of  the  Silky.  The  melanic  condition  affects  the 
periosteum  also.  It  is  remarkable  that  despite  this  excess  of  pigment  ren- 
dering black  the  internal  tissues,  skin,  leg  scutes,  comb,  and  wattles,  the 
plumage  should  be  always  white. 

MATERIAL. 

Mothers. — Four  Frizzles  (Nos.    14A,    i8a,    19A,  and  20A),  hatched  May, 

1904,  from  eggs  obtained  from  Dr.  A.  G.  Phelps,  of  Glen  Falls,  N.  Y.  All 
have  rose  combs  and  slightly  booted  feet.  No.  i8a  is  peculiar  in  that  the 
feathers  on  head  and  neck  are  sparse  and  small  (fig.  42).  In  general  color 
the  hens  vary  ;  i4Ais  prevaihngly  dark  brown  ;  i8a  is  yellowish  ;  19A  is  light 
brown,  and  20A  is  mixed  black,  yellow,  and  red.  A  male  Frizzle  from  the 
same  lot  of  eggs  was  highly  colored  red  and  black. 

Father. — A  white  Silky  cock  (No.  24A,  fig.  43),  likewise  hatched  from 
eggs  sent  in  May,  1904,  by  Dr.  Phelps. 

The  Silky  cock  and  Frizzle  hens  were  mated  from  January  16  to  April  14, 

1905.  Trap  nests  were  not  used,  so  that  I  could  distinguish  mothers  only 
by  the  form  of  the  eggs.  The  ^'g%  of  i8a  was  very  peculiar  and  was  early 
identified.  A  certain  proportion  of  the  offspring  can  not  be  assigned  to  any 
particular  mother. 

RESULTS. 

Only  the  first  hybrid  generation  has  been  obtained. 

1.  Plumage  Color. — Of  32  hybrids,  7  (22.6  percent)  are  white  (showing 
some  buff  in  six  cases)  and  25  (77.4  per  cent)  are  dark.  No.  i8a  appar- 
ently produced  only  dark  birds,  largely  dead-black.  The  others  produced 
in  part  white  hybrids  (fig.  44),  but  mostly  pigmented  ones.  The  result  is 
not  what  we  should  have  expected.  If  white  were  recessive,  o  to  50  per  cent, 
if  dominant,  100  per  cent,  of  the  offspring  should  be  white.  Moreover,  the 
Silky  is  doubtless  homozygous  in  respect  to  color,  since  (i)  Silkj-  fowls  are 
carefully  bred  for  white  color,  and  (2),  bred  to  a  hen  of  its  own  strain,  it  has 
produced  onl}^  white  birds.  I  conclude,  therefore,  that  the  white  plumage 
color  is  not  always  dominant  over  the  black,  red,  and  yellow  of  the  Frizzle. 
The  matter  will  be  further  investigated. 

2.  Comb. — In  all  cases  the  rose  comb  of  the  Frizzle  dominated  over  the 
single  comb  of  the  Silky  (fig.  44). 

3-5.  Curving  of  Shaft,  Barb  Length,  and  Barb  Form. — These  are  all 
correlated  in  the  first  generation.     Of  10  mature  birds,  6  are  typically  frizzled 


6o 


INHERITANCE    IN    POULTRY. 


and  4  have  flat  feathers.  Assuming  frizzling  to  be  dominant,  non-frizzling 
recessive,  and  that  all  my  Frizzle  fowls  are  heterozygous,  we  should  expect 
50  per  cent  frizzled  offspring.  The  result  accords  well  with  these  hypotheses. 
None  of  the  hybrids  show  any  trace  of  silkine.ss.  Silkiness  is  recessive  as 
against  non-silkiness. 

This  result  is  striking  and  has  been  observed  by  others.  Tegetmeier 
(1867,  p.  224)  bred  Silkies  to  other  varieties  and  found  that  "  the  chickens 
produced  seldom  had  the  silky  feathers,  but  were  clothed  in  plumage  of  the 
ordinary  character."  Mating  these  hybrids  together  he  got  among  plain 
feathered  offspring  "  one  covered  with  feathers  like  those  of  the  Silk  fowl," 
but  with  black  plumage.  Darwin  (1876,  Chapter  VII)  had  previously  bred 
a  white  Silk  hen  to  a  Spanish  cock  ;  ' '  none  inherited  the  so-called  silky 
feathers." 

6.  Number  of  Toes. — Thirty  hybrids  gave  the  following  distribution  of 
characteristics : 


Characteristic. 

/• 

Per  cent. 

4  toes,  both  feet 

4  and  5  toes 

7 
9 

14 

30 

23-3 
30.0 

46.7 

5  toes,  both  feet 

Total 

1 00.0 

Here,  as  elsewhere  in  this  paper,  the  inheritance  of  extra  toe  is  difficult  to 
account  for  on  the  Mendelian  principle  of  dominance. 

7.  Skin  Color. — All  hybrids  have  a  black  skin,  Tegetmeier  (1867, 
p.  224)  got  the  same  result. 

8.  Crest. — So  far  as  noted,  all  mature  hybrids  have  a  well-marked  crest, 
but  it  is  somewhat  smaller  than  that  of  the  Silky. 

CONCLUSIONS. 

A  final  conclusion  as  to  dominance  must  await  the  production  of  the  second 
generation  of  hybrids.  The  following  (in  italics)  appear  to  show  Mendelian 
dominance  over  the  corresponding  allelomorphs  : 

Rose  comb  vs.  vSingle  comb. 

Frizzle  feathers  vs.  Plain  feathers. 
Black  skin  vs.  White  skin. 

Crest  vs.  Plain  head. 

Plumage  color  and  number  of  toes  are  unit  characters,  but  behave  pe- 
culiarly.    The  dominance  of  the  crest  is  imperfect. 


LEGHORN   AND    RUMPLESS   GAME. 


6l 


Series  XII.— Single-comb  White  Leghorn  Bantam  and  Black-breasted  Red  Rumpless  Game. 

STATEMENT    OF   PROBLEM. 

This  cross  was  undertaken  primarily  to  test  the  inheritance  of  rumplessuess, 
and  secondarily  of  the  more  primitive  game  coloration  against  white  plumage 
color. 

THE  RACES  AS  A  WHOLE. 

The  White  I^eghorns  have  been  described  at  pages  37  and  39.  The  Black- 
breasted  Red  Game  closely  resembles  the  wild  Jungle  fowl  in  color  (figs. 
45  and  46). 

TABLE  OF  CHARACTERISTICS. 


REMARKS  ON  THE  CHARACTERISTICS. 

Uropygium. — The  absence  of  uropygium  is  a  characteristic  that  has  long 
been  known  among  fowl,  but  there  seems  to  be  little  knowledge  of  its  iror- 
phology.  In  ordinary  fowl  there  are  five  free  caudal  vertebrae,  followed  by 
a  fused  portion — the  uropygial  bone.  In  the  case  of  a  rumpless  Game  female 
(No.  119,  fig.  45)  dissected  by  me,  there  are  two  unsymmetrically  formed 
and  intimately  fused  vertebrae  behind  the  fifteenth  synsacral — the  posterior 
limit  of  the  sacral  vertebrae.  That  there  are  two  is  shown  by  distinct  trans- 
verse processes  with  spaces  of  the  passage  of  the  nerves.  Behind  these  is  a 
knob  of  bone  about  i  mm.  in  diameter.  These  three  elements  constitute 
the  entire  caudal  skeleton.     It  is  profoundly  reduced  from  the  normal. 

Rumplessuess  may  be  found  in  any  race.  It  has  cropped  out  in  two  of 
the  800  fowl  bred  at  this  station  in  the  past  year — hybrids  derived  from  the 
Minorca-Polish  and  the  Leghorn-Houdan  crosses.  It  seems  like  a  misuse 
of  the  term  breed  to  speak  of  a  "  Rumpless  breed,"  as  poultry  books  do. 

The  characteristic  is  referred  to  by  Aldrovandus  in  1645,  by  Temminck, 
and  by  other  early  writers.  Its  origin  has  been  ascribed  to  Persia,  to  Cey- 
lon, and  to  China  ;  doubtless  it  occurs  in  all  these  places  as  well  as  in  many 
others,  Taillessness  early  appeared  among  fowls  in  America.  Clayton 
(1693,  p.  992)  asserted  that  he  had  observed  that  in  "Virginia"  most  of  the 
cocks  and  hens  were  without  tails,  and  Wright  states  that  he  was  informed 
by  a  West  Indian  in  1872  "that  the  greater  number  of  fowls  in  his  own 
neighborhood  had  no  tails."  Darwin  (1S76,  Chapter  VIIj  refers  to  this 
characteristic  and  states  that  one  bird  he  examined  had  no  oil  gland;  the 
same  is  true   of  the  three  rumpless  Games  that  I  have  had.     Among  the 


62  INHERITANCE   IN   POULTRY. 

poultry  books  that  describe  the  "breed  "  quite  fully  are  Tegetmeier  (1867, 
pp.  230-232),  Baldamus  (1896,  pp.  170-172,  "  Kaul  oder  Kliitthiihuer  "  ), 
Diirigen  (1886,  pp.  98-100),  Wright  (1902,  p.  481),  and  Weir-Johnson- 
Bruwu  (1905,  pp.  1016-1017). 

Regarding  the  inheritance  of  this  characteristic,  statements  are  not  in 
accord.     Tegetmeier  (p.  231)  says: 

A  frieud  of  mine  purchased  a  successful  pen  [of  Rumpless  fowl]  at  a  poultry  show, 
taking  them  away  to  a  walk  where  no  other  fowls  ever  trespassed,  and  yet  the  chickens 
were,  in  a  considerable  number  of  instances,  furnished  with  fully  developed  tail  feathers, 
being  not  rnmpless.  On  inquiry  of  the  previous  owner,  he  stated:  "  Mine  have  always 
done  so  from  the  first  time  I  kept  them;  but  the  tailed  birds  will  very  probably  produce 
rumpless  chickens."  Three  such  birds  were  purposely  retained,  and  they  produced  the 
next  year  more  than  twenty  youngsters,  all  of  which  but  one  were  rumpless  and  destitute 
of  tail  feathers. 

The  foregoing  experiment  would  seem  to  prove  that  the  rumpless  parents 
were  heterogametous,  and  that  while  rumplessness  is  dominant  the  recessive 
conditionof  tail  is  here  prepotent  (Castle,  1905).  Darwin  (1876,  Chapter  VII) 
possessed  a  rumpless  bird  which  "  came  from  a  family  where,  as  I  was  told, 
the  breed  had  kept  true  for  twenty  years;  but"  he  adds,  "  rumpless  fowls 
often  produce  chickens  with  tails."  The  breeding  true  of  a  character  may 
mean  either  that  it  is  dominant  and  homogametoits  in  this  respect  or  that  it 
is  recessive.  Diirigen  (1886,  p.  99)  states  that  a  rumpless  cock  mated  with 
a  tailed  hen  produces  not  exclusively  rumple.ss,  but  a  fair  percentage  of  them, 
and  Wright  (1902,  p.  481)  saj'S  that  "  a  Rumpless  fowl  crossed  with  any  other 
generally  produces  a  large  majority  of  Rumpless  birds."  All  of  the  fore- 
going results  are  consonant  with  the  conclusion  that  rumplessness  is  typically 
dominant,  but  that  the  recessive  full  tail  may  be  prepotent. 

MATERIAL. 

The  mother  was  the  White  Leghorn  bantam  No.  127  discussed  at  page  39. 
She  is  heterozj^gous  and  contains  black  gametes. 

The  father  (No.  117,  fig.  46)  was  one  of  three  rumpless  bantams  obtained 
from  Dr.  A.  H.  Phelps,  of  Glen  Falls,  New  York.  Two  of  these  were 
typical  Black-breasted  Red  Games;  they  lack  oil  glands  and  weigh  about 
1,000  grams  each. 

RESULTS. 

Only  the  first  generation  of  hybrids  has  been  so  far  obtained. 

General  Plumage  Color. — Of  24  hybrids  12  were  white  or  prevailingly 
so  (fig.  47).  Usually,  however,  more  or  less  black  and  more  rarely  some 
buff  was  present.  The  other  12  were  either  black-and-white  barred  (and 
these  were  all  males)  or  black  with  more  or  less  reddish.  As  we  have  seen, 
the  white  mother  contains  recessive  black  or  black-and-white,  so  that  the 
result  accords  with  the  expectation  of  only  50  per  cent  white. 


BIwACK    COCHIN    AND    RUMPI.ESS    GAME. 


63 


Beak  Color. — In  the  hybrids  the  beak  is  sometimes  yellow,  sometimes 
black,  sometimes  black-and-yellovv  streaked. 

Uropygium. — Of  24  hybrids  the  uropygium  is  normal  in  23  (fig.  47). 
One  chick  taken  from  the  egg  is  recorded  as  without  tail,  though  tail  gland 
is  present.  It  is  doubtful  if  much  stress  may  be  laid  on  this  record,  as  the 
uropygium  is  always  ver}'  small  in  the  unhatched  bird.  We  may  exclude  it 
from  present  consideration.  This  whole  result  was  unexpected  because 
opposed  to  the  earlier  observations.  It  leads  to  the  provisional  hypothesis 
that  rumplessness  is  recessive  in  my  strain.  If  full  tail  is  recessive,  then  in 
my  strain  the  recessive  condition  is  prepotent.  Further  discussion  must  be 
deferred  until  the  second  hybrids  have  been  bred. 

Foot  Color. — This  was  3'ellow  in  about  half  of  the  cases  and  willow  or 
dark  in  the  other  half.  Recalling  that  the  White  Leghorn  is  heterozygous, 
the  result  favors  the  hypothesis  that  yellow  is  dominant  over  willow. 

CONCLUSIONS. 

White  plumage  color  seems  to  be  dominant  over  game  color.  The  hy- 
potheses seem  to  be  warranted  that  yellow  beak  and  foot  color  are  dominant, 
and  that  rumplessness  is  recessive  in  this  strain. 

Series  XIII,— Black  Cochin  Bantam  and  Black  Breasted  Red  Rumpless  Game. 

STATEMENT  OF  PROBLEM. 

This  cross  was  primarily  to  test  the  inheritance  of  rumplessness,  and 
secondarily  of  black  against  red  plumage  color. 

THE   RACES   AS   A   WHOLE. 

Concerning  the  Rumpless  Game  see  page  61.  The  Black  Cochins  are 
discussed  at  page  39. 

TABLE  OF   CHARACTERISTICS. 


No. 

Characteristic. 

Black  Cochin 
Bantam. 

Discussed 
at  page — 

Black-breasted   Red 
Rumpless  Game. 

Discussed 
at  page — 

I 

General  color. . . . 

Uropygium 

Iris  color 

Vulture  hock    . . . 
Foot  feathering.  . 

Black 

39 

63 

39 
34 

Red  with  some  black. 
Absent     

62 

2 
3 

4 
5 

Present 

Dark  brown  . , 

Present 

Present 

63 

•  • 

Red    streaked    with 

yellow 

Absent 

Absent 

MATERIAL. 

Mothers. — The  Black  Cochin  Bantams  Nos.  129  (fig.  26),  130,  131,  and 
132  were  the  same  as  those  referred  to  at  page  39. 
Father. — The  Rumpless  Game  is  No.  117,  referred  to  at  page  62  (fig.  46). 


64  INHERITANCE    IN    POULTRY. 

RESULTvS. 

Only  the  first  hybrid  geueration  has  been  produced. 

General  Plumage  Color. — Of  24  hybrids  all  were  prevailingly  black. 
Among  18  of  those  that  hatched  8  showed  some  red.  This  red  is  chiefly 
found  as  a  lacing  on  the  hackle  feathers  or  a  peppering  on  the  wing  coverts,-*^ 
throat, t  and  outer  margins  of  the  remiges.]:  This  seems  to  point  to  the 
hypotheses  that  while  black  dominates  over  red  the  dominance  is  sometimes 
imperfect.  When  red  occurs  it  occurs  on  those  feathers  that  normally  con- 
tain red  in  the  Game,  and  on  that  part  of  the  feather  that  is  red  in  the  Game. 

Uropvgium. — This  is  invariably  present,  apparently  fully  developed. 

Iris  Color. — All  the  hybrids  have  dark-brown  eyes;  only  one  shows  a 
trace  of  red.  The  hypothesis  seems  justified  that  in  this  case  dark-brown 
iris  pigment  is  dominant  over  red  and  yellow. 

Vulture  Hock. — This  is  always  absent.  In  only  a  single  case§  are  the 
feathers  slightlj^  elongated  on  the  hock. 

Foot  Feathering. — Ever}^  chick  that  hatched  has  the  foot  and  at  least 
one  toe  booted.  In  some  cases  this  booting  is  much  reduced  as  compared 
with  the  Cochin  parent.     Booting  is  dominant,  but  not  always  completely'  so. 

CONCLUSIONS. 

In  this  cross  of  black  vs.  red,  black  appears  to  be  dominant,  although  im- 
perfectly so.  The  two  colors  do  not  blend,  however,  but  red  appears  in  a 
particulate  fashion,  usually  in  the  parts  of  the  plumage  that  have  normally 
least  black  pigment.  It  is  as  if  there  were  a  struggle  between  the  two 
pigments  and  red  overcame  black  where  black  was  weakest. 

The  presence  of  tail  in  the  first  hybrid  generation  is  confirmatory  of  the 
results  of  the  preceding  series.     Rumplessness  is  apparentlj^  recessive. 

Brown  iris  color  appears  to  dominate  over  the  older  red,  and  booting 
dominates  over  the  ancestral  clean-footed  condition. 

*  Nos.  589  (^  and  798  c^.  t  No.  587  ?  •  t  No.  577  9  •  §  No.  651  J*. 


GENERAL   DISCUSSION.  65 

D.  GENERAL  DISCUSSION. 

INHERITANCE  OF  PARTICULAR  CHARACTERISTICS. 

COMB  FORM. 

The  comb  is  a  characteristic  that  has  had  its  origin  in  the  genus  Galhcs. 
It  consists  of  a  mass  of  uncovered  erectile  tissue — a  tissue  present  in  many 
species  of  birds.  The  primitive  form  of  the  corab  is  the  single  comb  seen 
in  the  wild  species  of  the  genus  Gallus,  and  in  most  domestic  races.  This 
may  be  modified  in  two  directions  :  First,  in  the  direction  of  lateral  repetition 
of  the  comb  giving  rise  to  the  pea  comb,*  and,  in  an  extreme  case,  to  the 
rose  comb  (of  which  the  walnut  comb  of  the  Malays  is  a  special  modifica- 
tion); second,  in  the  direction  of  reduction  of  the  modified  comb  producing 
the  races  with  mere  papillae  (Houdan,  Polish,  I,a  Fleche,  etc.)  or  that  are 
entirely  combless  (Breda  fowl).  That  the  rose  comb  is  a  modification  of  the 
same  sort  as  the  pea  comb  but  carried  to  a  greater  extreme  is  indicated  by 
the  fact  that  the  rose  comb  often  shows  five  parallel  ridges  (instead  of  the 
more  usual  irregularly  scattered  papillae)  and  that  in  the  female  the  ro.se 
comb  sometimes  consists  of  three  ridges  as  in  the  male  pea  comb. 

When  single  comb  (Minorca,  fig.  4)  and  pea  comb  (Brahma,  fig.  19)  are 
crossed,  pea  comb  is  dominant  (p.  35).  The  median  ridge  is,  however,  in 
the  hybrid  high  for  a  pea  comb  and  the  lateral  ridges  are  usually  reduced 
(figs.  20,  21).  When  single  comb  (Leghorn)  and  rose  comb  (Minorca)  are 
crossed,  rose  comb  is  dominant  (p.  30).  When  .single  comb  (Minorca  or 
Leghorn)  is  crossed  with  the  paired  rudiments  of  a  comb  found  in  the  Polish 
and  Houdan  fowl,  a  Y-shaped  comb  results  (pages  10,  22,  28,  fig.  8).  This 
Y  comb  is  of  great  interest.  It  was  obtained  by  Bateson  and  Punnett  (1905, 
pp.  108,  112-114)  in  some  of  the  offspring  of  (single-comb  Leghorn  x  rose- 
comb  Dorking),  crossed  with  (single-comb  Leghorn  x  walnut-comb  Indian)  ; 
and  also  in  one  of  the  offspring  of  a  single-comb  Leghorn  crossed  with 
[(single-comb  Leghorn  x  walnut-comb  Indian)  x  (single-comb  Leghorn 
X  rose-comb  Dorking)].  In  Bateson  and  Punnett's  cases  the  splitting  was 
evidently  nearly  complete,  forming  an  0-shaped  comb,  or  the  "cup  comb" 
of  Darwin  (1876,  Chapter  VII).  The  Y  comb  was  obtained  also  by  Hurst 
(1905,  pp.  133,  135,  138,  140,  146).  This  was  a  single  split  comb  when 
Leghorn  and  Houdan  were  crossed,  and  a  rose  split  comb  when  rose-comb 
Hamburgh  and  Houdan  were  mated. 

The  interrelation  of  the  different  forms  of  comb — single,  pea.  walnut, 
Y,  and  V  may,  I  think,  be  expressed  in  the  following  hypothesis  :  The  pea 
comb  and  the  walnut  comb  are  composed  of  two  element.s — a  median  single 
comb  and  a  pair  of  lateral  combs.     This  hypothesis  is  supported  by  the 


*The  pea  comb  was  doubtless  a  characteristic  of  the  unknown  feral  ancestor  of  the 
Aseel-Indian  group.     But  as  the  single  comb  is  the  dominant  type  in  the  known  wild 
Jungle  fowls  the  pea  comb  probably  evolved  from  it. 
5 


66  INHERITANCE    IN    POULTRY. 

following  evidence.  First,  of  teratology.  Extraneous  paired  papillae  occa- 
sionally occur  on  the  sides  of  the  single  comb  in  pure-bred  races.  These  are 
known  as  ' '  side  springs, ' '  and  are  considered  by  fanciers  as  grave  ' '  defects. ' ' 
Now  such  side  springs  are  morphologically  equivalent  to  the  lateral  ridges  of 
the  pea  comb.  Second,  there  is  the  evidence  of  hybrid  forms.  Bateson  and 
Punnett  (1905  a)  show  that  when  pea  comb  and  rose  comb  are  crossed  the 
second  hybrid  generation  (FJ  gives  single  comb,  as  well  as  pea  and  rose  combs. 
This  result  may  be  interpreted  as  due  to  the  fact  that  the  gametes  of  a  pea- 
combed  bird  have  either  a  tendency  toward  side-springs  (=  pea  comb)  or 
they  have  no  such  tendency  (:=  single  comb)  ;  and  the  gametes  of  a  rose- 
comb  bird  have  a  tendency  to  produce  two  pairs  of  side  combs  (=  rose  comb) 
or  else  the}'  have  no  such  tendency  (^=  single  comb).  When  two  gametes 
without  the  side-comb  tendency  come  together  in  F.^  a  single  comb  is  pro- 
duced. The  necessity  of  assuming  absence  and  presence  of  lateral  combs 
strengthens  the  view  that  the  pea  comb  is  made  up  of  two  elements — median 
and  lateral.  If  median  comb  and  side-springs  are  distinct  elements,  then 
they  should  be  independently  inheritable.  This  result  is  realized  on  the  one 
hand  in  the  single  comb,  and,  I  think,  on  the  other  hand,  in  the  cup  comb 
(fig.  6),  which  consists  of  two  side-springs  without  median  comb.  It  is 
realized  also  in  the  V  comb  of  the  Polish  fowl,  which  is  a  cup  comb  of 
which  the  anterior  portion  is  typically  not  developed. 

That  the  V  comb  represents  the  posterior  portion  of  a  cup  comb  is  supported 
by  the  fact  that  it  is  not  uncommon  to  find  not  one  pair  of  papillae  merel5^ 
but  two,  three,  or  four  pairs  of  papillae  in  Poli.sh  fowl  and  in  second-genera- 
tion hybrids.  A  row  of  three  or  four  papillae  on  each  side  of  the  head  is  a 
close  approach  to  a  typical  cup  comb. 

The  incompleteness  of  the  cup  comb  where  a  V  comb  is  produced  may  be 
due  to  various  causes.  In  the  Polish  fowl  the  upturned  nasal  process  and 
absence  of  a  bony  ridge  over  the  nostrils  appear  to  be  the  cause  of  the  absence 
of  a  comb  there,  and  we  have  seen  (p.  17)  that  the  only  undissociable  char- 
acteristics in  the  second-generation  hybrids  of  Minorca  and  Polish  are 
those  of  high  nostril  and  rudimentary  comb.  The  second  cause  restricting 
the  development  of  the  cup  comb  to  its  posterior  limits  is  the  presence  of  a 
median  comb  anteriorly  ;  this  is  the  case  of  the  ordinary  Y  comb.  The  Y  comb 
is  found  in  hybrids  between  .-^ ingle  and  V  comb  ;  the  anterior  portion  of  the 
comb  is  not  .suppressed  here,  because  th^  bony  roof  of  the  culmen  is  com- 
pletely developed,  and  the  very  presence  of  a  large  median  comb  there  prevents 
the  development  of  the  side-springs  at  the  same  niveau.  In  the  development 
of  the  comb  of  the  hybrid  there  is,  as  it  were,  a  .struggle  between  the  two 
elements  of  median  and  lateral  combs.  The  Ycomb  assumes  a  great  variety 
of  forms,  running  the  entire  gamut  from  a  single  comb  on  the  one  hand  to 
(i)  a  cup  comb  or  to  (2)  a  pair  of  papillae  on  the  other.  I  have  already 
(p.  10)  referred  to  the  variation  of  the  length  of  the  stem  of  the  Y,  series 


INHERITANCE  OF   PARTICULAR   CHARACTERISTICS.  67 

(i),froiu  100  per  ceuttouearlj-zero.  The  second  hj'brids  of  Polish  or  Houdans 
crossed  with  single  coiubs  illustrate  series  (2).  We  begin  with  a  single  comb 
having  its  posterior  one-sixth  split  ;  next  comes  a  comb  having  its  posterior 
one-sixth  split  and  anterior  five-sixths  single,  but  greatly  reduced  in  height 
(fig.  50) ;  next  the  same  with  the  anterior  portion  reduced  to  an  irregular 
carunculated  mass  having  a  slight  median  elevation  (fig.  49),  and  finally  a 
pair  of  papillae  only  (fig.  48).  In  this  series  we  have  a  fading  out  of  the 
median  portion,  pari  passu  with  the  enlargement  of  the  nostril,  but  the 
persistence  of  the  side  combs  unimpaired.  The  side  combs  have  been  unable 
to  enter  the  territory  from  which  the  median  comb  has  been  driven,  because 
that  territory  is  likewise  untenable  for  it.  These  two  series  sufficiently 
demonstrate  that  the  V  comb  represents  the  posterior  portion  of  the  cup  comb. 

That  the  cup  comb  represents  merely  the  greatly  enlarged  lateral  combs 
or  side-springs  is  proven  by  the  occasional  presence  of  both  median  and  cup 
comb  on  the  .same  individual.  In  some  races,  as  in  the  English  type  of  Hou- 
dans, the  median  comb  typically  appears  lying  between  the  pair  of  cup-like 
side-springs,  resembling  the  trunk  of  a  butterfly  between  its  wings.  Among 
the  heterozygous  combs  of  the  second  generation  of  Minorca  x  Houdan  or 
Minorca  x  Polish  hybrids,  instructive  examples  of  persistence  of  both  single 
comb  and  side-springs  are  especially  apt  to  occur.  Figure  52  shows  this 
condition  ;  there  is  a  median  comb  anteriorly  and  a  nearly  typical  pea  comb 
posteriorly,  except  that  the  lateral  ridges  are  atypically  high.  Thus  the 
Y  comb  becomes  explained  as  due  to  the  presence  of  both  single  and  lateral 
combs. 

The  question  now  arises,  Is  it  possible  to  explain  on  Mendeliau  principles 
the  production  of  a  Y  comb  when  median  comb  and  lateral  comb  are  crossed  ? 
In  accordance  with  such  principles  we  should  have  to  picture  the  gametes 
of  the  single-comb  and  V-comb  parents  as  follows  : 


Single  comb. 

V-comb. 

Median  element 

No  lateral  elements   .  . 

No  median  elements. 
Lateral  elements. 

The  allelomorphs  are  then  median  and  no  median,  no  lateral  and  lateral, 
and  the  positive  characteristics  are  dominant.  In  the  .second  hybrid  gen- 
eration the  two  dominant  characters  should  be  combined  in  nine-sixteenths 
of  all  cases  ;  the  two  recessive  in  one-sixteenth,  and  one  dominant  with  one 
recessive  in  three-sixteenths  +  three-sixteenths  of  the  cases. 

Another  hypothesis  is  possible.  Granting  that  the  Y  comb  is  no  neomorph, 
but  the  sum  of  single  and  lateral  comb,  then  the  Y  comb  may  be  a  case  of 
particulate  inheritance,  the  median  comb  being  produced  on  the  anterior  and 
the  lateral  on  the  po.sterior  part  of  the  frontal  region.     In  cases  of  particulate 


68 


INHERITANCE   IN   POULTRY. 


hybrids  bred  inter  se,  the  offspring  exhibits  oue  or  the  other  of  the  parental 
conditions  each  in  25  per  cent  of  the  cases  and  the  heterozygous  condition 
in  50  per  cent.  To  decide  between  these  rival  hypotheses  we  have  to  appeal 
to  the  statistics  of  occurrence  of  the  different  forms  of  comb.  All  cases 
(Series  I  and  II}  are  combined  in  the  following  table,  showing  distribution 
in  the  second  hybrid  generation  : 


Comb  characteristic. 

Expected. 

Actual. 

On  hypothesis 
of  dominance. 

On  hypothesis 

of  particulate 

inheritance. 

Single  comb 

Y  comb   . 

Lateral  comb .... 

No  comb 

Per  cent. 

18.75 
56.00 

Per  cent. 
25 

5' 

25 

0 

Per  cent. 
30.1 

44-9 
25.00 

0? 

The  foregoing  table  reveals  several  things.  First,  the  actual  distribution 
of  comb  form  in  the  second  generation  accords  better  with  the  hypothesis  of 
particulate  inheritance  than  that  of  dominance  of  both  single  and  lateral 
comb.  That  there  is  an  excess  of  single  comb  and  deficiency  of  Y  comb  is 
partly  accounted  for  by  occasionallj'  counting  a  potentially  Y  comb  but 
actually  single  (or  nearl)-  single)  comb  as  a  true  .single.  Secondlj^  the 
hypothesis  of  dominance  demands  the  occurrence  of  a  fourth  form — pre- 
sumably no  comb — in  6^  per  cent  of  the  cases.  No  combless  fowl  was 
raised  to  maturity,  and  the  only  possible  cases  were  seen  in  still  very  j^oung 
or  unhatched  chicks.  Probably  no  true  combless  bird  appeared.  From 
both  of  these  considerations  I  conclude,  provisionall}^  in  favor  of  the  theory 
that  the  Y  comb  is  reproduced  from  the  median  and  the  lateral  by  particidai^ 
inheritance. 

NOSTRIIv  FORM. 

The  sum  of  results  in  Series  I,  II,  and  III  (narrow  x  high  nostril)  gives  : 


Generation. 

Narrow  and  intermediate. 

High. 

/. 

Actual. 

Expected. 

/• 

Actual. 

Expected. 

Fi 

F2 

Fi  X  narrow 

102 
99 
33 

Per  cent. 
99.0 
73-9 
51-5 

Per  cnt. 

100 

75 
50 

I 
35 
31 

Per  cent. 
I.O 

26.1 
48.5 

Per  cent. 

0 

25 
50 

A  close  agreement  exists  between  the  percentage  obtained  in  each  genera- 
tion and  the  expectation  on  the  Mendelian  theory,  assuming  that  narrow 
nostril  is  dominant.  The  statistics  do  not,  how^ever,  tell  the  whole  story. 
In  36  per  cent  of  the  cases  in  the  Fj  generation  the  nostril  was  wider  than  in 


INHERITANCE   OF    PARTICULAR   CHARACTERISTICS. 


69 


the  ' '  narrow ' '  ancestor.  Even  in  the  F,^  generation  nearly  half  of  the  ' '  nar- 
row and  intermediate"  were  of  the  intermediate  sort.  This  intermediate 
form  is  evidence  that  dominance  is  imperfect  and  segregation  is  incomplete. 

CEREIJRAI.   HKRNIA. 

Cerebral  hernia  is,  as  already  pointed  ont,  a  typical  monstrosity.     The 
distribution  of  its  occurrence  in  crossing  is  as  follows  : 


Crosses. 

Fi- 

F,. 

Fi  X  plain. 

Plain. 

Hernia. 

Plain. 

Hernia. 

Plain. 

Hernia. 

Minorca  X  Polish 

66 

24 
16 

106 

0 

0 
*o 

0 

75 
34 

109 

23 
II 

34 

34 
25 

59 

0 

White  L,eghorn  X  Houdan.  . 
Houdan  X  Minorca     .    ... 

to 

Total 

0 

Percentage 

100 

0 

76.1 

239 

TOO 

0 

*  Excludiug  one  case  of  egg  embryo  with  cerebral  vesicle. 
t  Excluding  one  egg  embryo  recorded  as  doubtful. 

Cerebral  hernia  is  inherited  in  Mendelian  fashion  with  plain  head  domi- 
nant. Nevertheless,  many  of  the  plain-headed  hybrids  have  the  frontal 
eminence  abnormally  high — -dominance  is  imperfect. 

CREST. 

The  crest  is  independent  of  the  cerebral  hernia  (pages  16-18).  It  is  a 
widespread  characteristic  among  birds,  so  common  that  it  is  not  readily 
thought  of  as  pathological  but  usually  as  ornamental.  The  distribution  of 
iis  occurrence  in  crossing  is  as  follows  : 


Crosses. 

F.. 

F^. 

Fi  X  plain. 

Plain. 

Crested. 

Plain. 

Crested. 

Plain. 

Crested, 

Minorca  X  Polish        

0                 70 

II 
6 

•    a 

17 

1 

1                     - 
41             1                     fi 

6 

White  Leghorn  X  Houdan.  . 

Houdan  X  Minorca .  . 

Frizzle  X  Silky 

01000 

25 
9 
5 

109 

13 

6 

9 

Total 

54 

12 

15 

Percentage 

0 

100 

24 

76 

44.5 

55-5 

Crest  is  inherited  in  Mendelian  proportions,  and  is  dominant  over  crestless 
head.  Even  when  the  Silky  is  crossed  with  Gallus  bankiva  its  crest  is  domi- 
nant (fig.  53).  In  this  case  the  new  characteristic,  a  positive  variant,  domi- 
nates over  the  ancient  one  ;  but  the  crest  is  diminished  in  the  first  genera- 
tion ;  dominance  is  imperfect. 


INHERITANCE    IN   POULTRY. 


WHISKERS  OR  MUFF. 


This  is  certainly  a  new  character  and  a  positive  variant.     The  distribution 
of  its  occurrence  in  crossing  is  as  follows  : 


Crosses. 

F.- 

F,. 

Fi  X  plain. 

Absent. 

Present. 

Absent. 

Present. 

Absent. 

Present. 

Leghorn  X  Houdan 

Houdan  X  Minorca 

o 
o 

24 
II 

? 

26 
26 

5 
5 

II 

Total 

o 

35 

? 

II 

Muffling  is  apparently  dominant. 


BEARD. 


This  is  also  a  new,  positive,  variant.     The  distribution  of  its  occurrence 
is  as  follows  : 


Crosses. 

Fi- 

F.. 

Fi  X  plain. 

Absent. 

Present. 

Absent. 

Present. 

Absent. 

Present. 

Leghorn  X  Houdan 

Houdan  X  Minorca    .      ... 

0010 

23 

10 

33 

? 

12 

3 

8 

Total 

? 

12 

3 

8 

Beard  is  apparently  dominant,  but  often  imperfectly  so. 

FEATHER  FORM. 

Silkiness  is  a  new  characteristic  and,  approximating  as  it  does  the  juvenile 
down  condition,  a  negative  one.  When  a  Silky  is  crossed  with  a  Jungle  fowl 
the  offspring  are  plain.  Silkiness  is  recessive  to  non-silkiuess — the  retrograde 
to  the  progressive  type. 

Frizzling  is  likewise  a  new  characteristic — a  positive  character  added  to 
the  perfect  feather.  The  distribution  of  the  occurrence  of  silkiness  and  friz- 
zling is  as  follows  : 


The  Frizzle  fowl  used  were  doubtless  heterozygous.  When  non-frizzled 
birds  are  crossed  inter  sc  they  produce  only  plain  offspring.  Frizzling  is 
dominant  over  non-frizzling — the  progressive  over  the  primitive. 


INHERITANCE   OF   PARTICUI.AR   CHARACTERISTICS. 


71 


UROPYGIUM. 


Rumplessness  is  a  new  characteristic  and  a  typical  negative  variant.     The 
distribution  of  its  occurrence  is  as  follows  : 


Fi- 

Non-rumpless. 

Rumpless. 

Leghorn  X  Rumpless  Game 

Cochin  X  Ruuipless  Game 

23 

19 

7 

3 

*o 
0 
0 
0 

Frizzle  X  Rumpless  Game 

Nankin  X  Rumpless  Game 

Total .    

Percentage  

52 

0 

IOC 

0 

*  One  egg  embryo  doubtfully  rumpless. 

The  new,  negative  characteristic  is  here  completely  recessive. 

TAIL-I,ENGTH. 

The  long  tail  of  the  male  Tosa  fowl  is  a  new,  positive  variant.     The  dis- 
tribution of  its  occurrence  in  male  hybrids  is  as  follows  : 


Crosses. 

Fi- 

F,. 

Short. 

Long. 

Short. 

Long. 

Tosa  X  Cochin 

Brahma  X  Tosa 

Total 

0 
0 

3 
*i6 

? 

? 

0 

19 

*  Tlie  tails  are,  perhaps,  more  properly  intermediate.    While  still  growing  at  date  of  record,  they 
grow  slowly. 

The  new,   positive  characteristic  is  doubtfully  dominant,  possibly  inter- 
mediate {cf.  fig.  34). 

VUI^TURE  HOCK. 

This  bundle  of  strong  feathers  constitutes  a  new,  positive  characteristic. 
The  distribution  of  its  occurrence  is  as  follows  : 


Cros.ses. 

F,. 

F,. 

Absent. 

Present. 

Absent. 

Present. 

Minorca  X  Brahma 

7 
12 
12 

9 

t3 
All  j 

III 

*o 
0 

(Small)  I 
0 

t3 
trades. 

0 

16 

t  20 

Leghoru  X  Brahma 

Black  Cochin  X  Leghorn 

Leghorn  X  Buff  Cochin 

Tosa  X  White  Cochin 

Brahma  X  Tosa 

Black  Cochin  X  Rumpless  Game. 

*  One  shows  trace  of  enlargement  ot  teathers. 
t  Females  with  vulture  hock  ;  males  without  it. 


X  Seven  recorded  as  slight. 

S  Oue  case  of  trace  of  elongation  of  feathers. 


72  INHERITANCE    IN    POULTRY. 

The  result  is  peculiar.  Usually  the  vulture  hock  is  absent  iu  the  first 
hybrids,  indicating  its  recessiveuess.  In  crosses  with  a  particular  race — 
Tosa  fowl — however,  there  is  no  recessiveuess.  It  is  probable  that  the  Tosa 
fowl  is  heterozygous  iu  respect  of  this  characteristic.  The  new  character- 
istic is  recessive,  but  imperfectly  so. 

FOOT  FEATHERING. 

Foot  feathering,  as  the  discussion  on  page  34  indicated,  is  a  positive  vari- 
ation, new  to  Gallus,  but  not  of  a  pathological  sort.  Common  among  wild, 
scratching  birds,  its  occurrence  in  Gallus  may  be  regarded  as  a  case  of  de- 
gressive variation  (de  Vries).     The  distribution  of  its  occurrence  is  as  follows  : 


Crosses. 

Fi-                               F.. 

Non- 
booted. 

Booted. 

Non- 
booted. 

Booted. 

Minorca  X  Dark  Brahma 

Leghorn  female  X  Dark  Brahma 

male 

Dark   Brahma  female   X    LfCg- 

horn  male 

Black  Cochin  X  Leghorn 

Leghorn  X  Buflf  Cochin 

Tosa  X  White  Cochin      

Dark  Brahma  X  Tosa 

Frizzle  X  Silky 

Black  Cochin  X  Rumpless  Game . 

Total 

I 

4 

0 
0 

3 
0 
0 

3 
0 

40 
15 

25 
20 
26 

7 
22 

15 
21 

7 

48 

II 

191 

7 

48 

The  foregoing  statistics  tell  only  a  part  of  the  story.  Booting,  when 
present,  is  frequently  much  reduced  ;  one  may  regard  absence  of  booting  as 
the  extreme  condition.     Booting  is  dominant,  but  usually  imperfectly  so. 


EXTRA    TOES. 

The  extra  toe  is  a  positive  variation  of  a  teratological  sort, 
tion  of  its  occurrence  is  as  follows  : 


The  distribu- 


Pi. 

F,. 

Fi  X  normal. 

Crosses. 

No  extra 
toe. 

Extra 
toe. 

No  extra 
toe. 

Extra 
toe. 

No  extra 
toe. 

Extra 
toe. 

Houdan  X  Leghorn 

Houdan  X  Minorca 

Frizzle  X  Silky 

6 
6 

7 

19 

31 
15 
23 

17 
17 

6 

■■ 
6 

17 

8 

Total 

69 

17               S 

Percentage 

21.6 

78.4 

73-9 

26.1 

68.0 

32.0 

INHERITANCE    OF    PARTICULAR    CHARACTERISTICS.  73 

These  results  are  peculiar.  If  both  normal-toed  and  extra-toed  ancestors 
were  heterozygous  in  respect  to  toes,  we  should  expect  the  result  obtained  iu 
Fp  It  is  quite  possible,  though  not  probable,  that  this  is  true.  Then  extra 
toe  would  be  dominant,  although  sometimes  so  imperfectlj^  so  as  not  to 
appear.  In  F,  the  parents  were  normal-toed,  either  because  "normal"  is 
recessive  or  because  it  is  imperfectly  dominant.  All  offspring  should  be 
normal-toed  in  the  one  case  or  give  100  per  cent  to  75  per  cent  extra-toed 
in  the  other.  The  result  is  not  in  accordance  with  either  hypothesis.  If 
there  is  any  dominance  in  this  generation  it  is  of  the  7iormal  toe.  Bateson 
and  Saunders  (1902,  p.  124),  while  concluding  that  extra  toe  is  dominant, 
find  "that  the  recessive  foot  character  may  sometimes  dominate."  Hurst 
(1905,  p.  150)  also  got,  in  a  cross  between  Iveghorn  and  Houdan,  some 
normal-toed  ofifspriug  which,  interbred,  produced  extra-toed  progeny.  He 
concludes  that  a  usually  dominant  character  may  recede  in  certain  individ- 
uals. There  is  danger  here  of  straining  Mendel's  law.  It  is  better  to  hold 
' '  explanations  ' '  in  abeyance  until  the  matter  of  inheritance  of  polydactylism 
has  been  more  thoroughly  investigated.  Certainly  the  facts  of  inheritance 
of  polydactylism  in  man  can  hardly  be  explained  on  Mendelian  principles 
(Davenport,  1904).  Polydactylism  is  at  least  not  recessive.  The  new,  posi- 
tive, pathological  characteristic  holds  its  own  against  the  older  one. 

SKIN  COLOR. 

The  epidermis  of  poultry  is  everywhere  covered  by  feathers  except  on  the 
beak,  face,  and  feet.  The  naked  portions  may,  however,  have  a  different 
color  from  the  covered  ones  ;  consequently  the  correlation  between  general 
skin,  beak,  and  foot  color,  although  not  absent,  is  not  close.  Thus,  although 
the  yellow  beak  and  foot  of  the  lyCghorn  are  correlated  with  its  yellow  skin, 
the  black  legs  and  beak  of  the  Black  Minorca  are  not  accompanied  by  a 
black  skin.  Not  all  exposed  parts,  even  of  the  skin,  are  of  one  color,  for  the 
face,  at  least,  maybe  red  or  white  when  the  legs  are  black.  Color  of  beak 
and  foot  are,  on  the  other  hand,  closely  correlated,  individual  variations  of 
the  one  being  usually  associated  with  corresponding  variations  of  the  other. 
This  correlation  is  doubtless  the  result  of  the  similar  cornification  of  the  skin 
of  beak  and  foot,  whereas  (excepting  races  with  opaque  white  face)  the 
vascular  face  and  earlobes  are  white  or  red,  according  to  a  less  or  greater 
blood  supply  in  them. 

The  pigmentation  of  the  epidermis  of  poultry  falls  into  three  classes  :  (a) 
Without  pigment  or  white  ;  [U)  yellow  ;  {c)  black.  White  skin  is  the  com- 
monest, even  among  poultry  with  black  plumage  and  feet.  Yellow  skin  is 
found  in  the  Asiatics,  derived  from  the  Aseel- Malay  ancestry,  and  is  a  char- 
acteristic of  the  White  Leghorn.  Black  pigment  occurs  in  the  skin  of  the 
Silky  fowl  and  the  Negro  fowl.  Black  pigment  is  to  be  regarded  as  a  new 
variant  and  of  the  nature  of  a  pathological  sport — melanism.     When  black 


74  INHERITANCE    IN    POULTRY. 

skill  is  crossed  with  white,  black — the  new,  positive,  pathological  character- 
istic— is  dominant  (page  60). 

MANDIBLK   COLOR. 

The  prevailing  types  are  black,  willow,  yellow,  and  white.  Black  is  the 
primitive  color  on  the  Jungle  side  ;  yellow,  on  the  Aseel  group.  When  horn 
(Houdan)  and  yellow  (Leghorn)  mandible  colors  are  crossed,  the  first  genera- 
tion shows  the  yellow  of  the  Leghorn,  which  is  dominant.  When,  however, 
the  black  beak  of  the  Minorca  was  crossed  with  the  yellow  beak  of  the 
Brahma,  the  dark  color  dominated.  The  potency  in  the  hybrid  of  beak  color 
seems  to  follow  this  series  :  Black,  yellow,  horn.  The  most  positive  char- 
acter, black,  dominates  all. 

FOOT  COLOR. 

Four  principal  types  are  to  be  distinguished — willow,  black,  yellow,  and 
white.  Willow  is  primitive  and  white  the  most  aberrant.  The  results  are 
based  on  still  insufficient  data,  but  so  far  as  they  go  they  indicate  that  willow 
is  dominated  by  yellow  (p.  54),  yellow  by  white  (p.  24),  and  white  by  black 
(p.  28).  The  newer,  negative  characteristic,  white,  is  dominant  over  the 
older  yellow,  but  the  new,  positive  characteristic  of  melanism  dominates  all. 

IRIS   COLOR. 

Of  the  various  forms,  pearl  to  yellow  is  characteristic  of  the  Aseel  type  ; 
red,  of  the  Game  or  Gallics  bankiva  type.  Black  has  become  associated  with 
black  plumage.  The  results,  subject  to  revision,  indicate  that  in  poultry, 
as  in  man,  iris  color  rarely  blends,  that  red  dominates  pearl  (page  38),  and 
that  dark  brown  dominates  red.  The  new,  positive  variation  of  melanism 
seems  to  dominate  all,  although  not  alwaj's  perfectly. 

EARLOBE  COLOR. 

Red  is  primitive  in  both  groups.  White  is  a  new  variation,  which  is  prob- 
ably due  to  fat  or  other  particles  in  the  skin,  and  is  consequently  positive. 
Only  in  extreme  cases  is  red  wholly  eliminated  from  the  earlobe.  In  three 
series  of  crosses  (V,  VI,  and  X)  of  the  red-lobed  Dark  Brahma  and  a  white 
(and  red)  lobed  race  the  earlobes  were  prevailingly  red,  but  had  some  white 
at  their  centers.  Likewise,  in  two  series  of  crosses  (VII  and  VIII)  of  the 
red-lobed  Cochin  and  a  white- lobed  Leghorn,  red  dominated  in  the  hybrids, 
but  did  not  always  perfectly  exclude  white.  Red  is  apparently  dominant, 
but  very  imperfectly  so  ;  some  cases  rather  indicate  particulate  inheritance. 

GENERAL  PLUMAGE  COLOR. 

The  original  plumage  as  exhibited  in  the  Jungle  fowl  is  largely  black  and 
red  ;  that  of  the  Aseel  type  sometimes  contains  much  white  ;  but  the  pure 
white  plumage  must  be  regarded  as  a  new  negative  variant.  The  outcome 
of  crossing  is  complex. 


INHERITANCE    OF    PARTICULAR    CHARACTERISTICS.  75 

White  vs.  Dark — Three  different  results  may  be,  under  differing  condi- 
tions, obtained. 

Dominance  of  White. — This  is  the  usual  result.  Tu'o  White  Leghorns 
crossed  by  a  black  Minorca  produced  only  white  hj'brids,  but  the  female 
hybrids,  at  least,  had  some  black  feathers.  White  Leghorns  crossed  with 
Houdans  gave  only  v/hite.  White  Leghorns  crossed  with  a  Red-backed 
Game  had  white  offspring  with  some  buff  on  breast.  On  the  other  hand, 
the  white  color  of  the  Silkj-  dominates  over  the  dark  color  of  the  Frizzle 
CSeries  XI)  in  about  only  23  per  cent  of  the  hybrids.  Bateson  and  Saunders 
(1902,  pp.  108-109),  dividing  all  hybrids  between  black  and  white  parents 
into  those  of  light  type  and  those  of  dark  type,  conclude  that  the  former 
are  to  the  later  as  3.1  to  i.  Bateson  and  Punnett  (1905,  p.  117)  conclude 
that  offspring  of  a  pure  white  parent  with  colored  or  heterozygous  (mixed) 
birds  are  practicallj^  always  prevailingly  white.  Hurst  (1905,  pp.  146-149) 
gets  chiefly  white  birds  from  crosses  of  White  Leghorn  hens  with  black  or 
mottled  males.  The  exceptions  may  be  due  to  the  impurity  of  one  of  the 
females. 

Barring. — No  barring  resulted  from  crossing  White  Leghorn  withHoudan 
or  black  Minorca,  or  vSilky  with  Frizzle.  On  the  other  hand,  all  males,  and 
only  males,  were  barred  in  the  hybrids  of  Tosa  x  White  Cochin,  and  in  the 
hybrids  of  White  Leghorn  Bantam  and  Rumpless  Game  barring  occurred, 
but  among  males  only.  Of  26  hybrids  between  Black  Cochin  and  White 
Leghorn,  8  were  barred  black  and  white,  and  these  belonged  equally  to  the 
two  sexes.  Of  11  dark  h5'brids  obtained  by  Hurst  (1905,  p.  133)  frooi 
White  Leghorn  x  Houdan,  6  developed  into  black  females  and  5  into  cuckoo 
males.  Apparentl}^  barring  ("cuckoo  marking"  of  the  English)  is  asso- 
ciated with  maleness.  This  result  is  curious  enough,  for,  as  Darwin  pointed 
out,  in  the  ancestors  of  domestic  poultry  barring  (or  rather  penciling)  is 
confined  to  the  female  sex. 

Barring  is  a  heterozygous  condition  found  in  hybrids  from  a  white  and 
a  black  parent.  It  is  provisionally  regarded  as  a  form  of  particulate  inherit- 
ance as  opposed  to  the  alternative  inheritance  of  the  Leghorn  x  Minorca 
cross.  This  heterozygous  condition  when  interbred  usuall}-  breaks  up  into 
white,  uniformly  pigmented,  and  barred  again,  as  in  the  case  of  the  Tosa 
X  White  Cochin  hybrids  (p.  49).  This  form  has  in  certain  cases,  as  in  the 
Cuckoo  Dorkings  and  in  the  Dominiques — ancestors  to  the  Plymouth  Rocks — 
become  truly  mosaic,  transmitting  the  mixture  of  qualities  pure.  The 
method  of  fixing  a  heterozygous  quality  is  still  unknown  to  science.* 

*The  experience  of  breeders  of  mice  and  guinea-pigs  shows  that  white  may  be  due  to 
the  absence  of  an  oxidizing  ferment  necessary  to  the  bringing  out  of  the  color  potential  in  a 
chroaiogenic  substance  (<■/.  von  Fiirth,  1903).  If  the  chrouiogen  is  present  the  addition 
(by  crossing  with  a  pigmented  individual)  of  the  ferment  will  reveal  in  the  hybrid  ofY- 
spring  the  colors  and  pattern  latent  in  the  white  parent.  Working  on  this  hypothefis, 
we  can  judge  of  the  latent  patterns  in  the  White  Leghorn  bantams  and  draw  conclusions 


76  INHERITANCE    IN    POULTRY. 

Andalusian  Coloration. — Among  the  ofiFspring  of  a  White  Leghorn  and  a 
Black  Minorca  two  adult  blue  fowls  were  reared  (fig.  54) .  The  coloration 
was  that  of  the  Andalusian  "breed."  It  consisted  of  a  minute  patchwork 
of  black  and  white  pigment.  Such  a  blue  coloration  is  common  in  barn-yard 
fowls.  It  results,  according  to  the  testimony  of  breeders,!  from  crossing 
black  and  white. 

The  special  conditions  which  determine  whether  the  offspring  of  a  white 
and  a  black  parent  shall  be  all  white  or  barred  or  blue  have  not  yet  been 
determined.  The  solution  of  this  problem  oflfers  one  of  the  most  interesting 
fields  for  future  investigation  (p.  30). 

White  vs.  Buff. — Both  colors  are  novel ;  the  former  is  probably  a  nega- 
tive mutation  ;  the  latter  has  been  extracted  from  the  original  game  colora- 
tion of  fowls.  The  hybrids  are  prevailingly  white,  and  white  may  be 
regarded  as  dominant.  Nevertheless,  this  dominance  is  imperfect,  for  in 
half  of  the  offspring  buff  is  more  or  less  evident.  It  is  found  diffused  over 
the  back,  wings,  and  breast  as  in  "  pile"  Games.  On  the  whole,  white  is 
less  strongly  dominant  over  buff  than  it  is  over  black  (Hurst,  1905,  p.  134). 

Black  vs.  Red. — The  red  coloration  is  ancestral ;  the  solid  black  is  novel 
and  positive — a  melanic  condition.  The  hybrids  between  Black  Cochin  and 
Red-breasted  Game  are  prevailingly  black,  but  about  half  of  them  show  red 
lacing  on  the  hackle  feathers  or  a  red  peppering  in  those  places  where  red  is 
displayed  by  the  Game.     Black  is  dominant  over  red,  but  imperfectly  so. 

COLOR  OF  TOP  OF  HEAD. 

In  the  white-crested  Black  Polish  the  feathers  of  the  top  of  the  head  are 
in  striking  contrast  to  those  over  the  rest  of  the  body.  That  the  crest  is  not 
necessarily  white  is  proven  by  the  existence  of  a  black-crested  race.  Hybrids 
between  the  Minorca,  whose  head  is  wholly  black,  and  the  Polish  give  (p. 
15)  chiefly  black  feathers  in  the  males,  the  females,  however,  still  showing 

as  to  what  pigmeated  ancestors  they  may  have  had.  They  were  used  iu  five  crosses,  as 
follows  :  (i)  Black  Cochin  X  White  Leghorn;  (2)  White  Leghorn  X  BnflF  Cochin;  (3) 
White  Leghorn  X  Black-breasted  Red-backed  Game  ;  (4)  White  Leghorn  X  Dark 
Brahma  ;  (5)  Dark  Brahma  X  White  Leghorn. 

Taking  all  offspring  together,  about  50  per  cent  (48.5)  are  white  or  nearly  so.  All 
crosses  exhibit  barring,  together  in  about  one-quarter  (26,5)  of  the  cases,  and  also  black 
and  buff  or  red.  It  seems  probable  that  all  of  these  pigments  and  the  barred  pattern 
are  latent  in  my  White  Leghorn  bantams.  These  conclusions  are  supported  by  breed- 
ing the  White  Leghorns  inter  se,  when,  in  addition  to  white  offspring,  a  black  and  a 
barred  were  obtained  (p.  40).  Similarly  among  the  second  hybrids  between  theTosa  and 
White  Cochin  Bantam  there  appeared  a  male  and  a  female  resembling  in  plumage  colora- 
tion the  Partridge  Cochins  (p.  49).  This  coloration  probably  lay  latent  in  the  gametes 
of  the  White  Cochin. 

t  Compare  Darwin  (1876,  I,  Chapter  VII  ;  1S94,  I,  p.  270)  ;  Wright  (1902,  pp.  291,  292, 
317.  301.  399.  401,  etc.)  ;  Bateson  and  Saunders  (1902,  p.  131)  ;  Bateson  and  Punnett 
(1905,  p.  126).  When  blues  are  interbred,  the  offspring  are  either  white  or  black  or  blue. 
Even  in  the  Andalusian  "  breed  "  the  blue  coloration  has  never  become  fixed. 


INHERITANCE   OF   PARTICULAR   CHARACTERISTICS.  77 

white  in  their  crests.  The  hybrids  crossed  back  on  the  Minorca  give  nearly 
100  per  cent  black  heads.  Black  is  dominant,  but  imperfectly  so  ;  the  nega- 
tive characteristic  is  recessive.  The  dominant  character  is  less  perfectly 
dominant  in  the  female  sex  than  in  the  male. 

COr.OR  OF  HACKI.es— HACKLE  LACING. 

The  color  of  the  hackle  feathers  and  the  correlated  saddle  feathers  in 
birds  of  broken  color  usually  differs  from  that  of  the  rest  of  the  plumage. 
This  peculiarity  of  the  hackle  coloration  is  an  old  character,  since  it  is 
exhibited  by  the  Jungle  fowl,  and  was  probably  in  the  ancestor  of  the 
Aseel-Malay  group.  The  feathers  are  laced  with  a  lighter  color  than  the 
center. 

In  crosses  between  Minorca  and  Dark  Brahma,  and  White  Leghorn  and 
Dark  Brahma  the  solid  color  (black  or  white),  the  new,  positive  character- 
istic, dominates  over  the  lacing.  Nevertheless,  in  the  Minorca  X  Dark 
Brahma  hybrids  the  feathers  of  the  nape  are  frequently  faintly  laced  with 
gray.     The  black  is  imperfect!}'  dominant. 

WING  COLOR— RED  WING  COVERTS. 

The  male  Jungle  fowl  has  red  on  the  upper  wing  coverts,  and  doubtless 
the  male  of  the  ancestors  of  the  Aseel-Malay  group  had  also. 

The  male  hybrids  between  the  Dark  Brahma  and  the  Black  Minorca  on 
the  one-hand  and  the  White  Leghorn  on  the  other  usually  shovv'  red  on  the 
wing  coverts,  although  there  is  no  other  red  in  the  plumage.  Red  on  the 
wing  coverts  is  probably  dominant,  but  it  is  much  reduced. 

TAIL  COLOR. 

Although  the  tail  feathers  are  derived  from  a  distinct  feather  tract,  and  in 
broken-colored  birds  are  usually  without  the  red  of  the  wing,  yet  tail  color 
does  not  seem  to  be  a  unit  character  ;  in  inheritance  it  follows  the  rest  of  the 
body  plumage.  On  the  other  hand,  in  breeding  buff  varieties  black  persists 
in  the  tail  feathers  longer  than  in  the  others.  This  case  resembles  the  per- 
sistence of  black  at  the  extremities  of  the  legs  of  white  or  red  rabbits 
(Castle,  1905). 

.SHAFTING. 

The  female  Jungle  fowl  has  a  light  shaft  to  the  feather.  The  same  is 
true  of  the  Tosa  fowl  and  some  Games.  Light  shafting  is  a  primitive 
characteristic  of  the  female. 

In  the  female  hybrids  between  the  Tosa  fowl  and  White  Cochin  the  shaft- 
ing is  greatly  broadened,  and  this  is  the  principal  modification  of  the  plumage 
color.  In  female  hybrids  of  the  Tosa  fowl  and  Dark  Brahmas  the  shafting 
of  the  feathers  of  the  back  and  wing  coverts  is  striking,  and  some  shafting 
appears  in  two  of  the  males,  probably  transferred  from  the  female  (p.  54). 
Apparently  shafting  is  dominant. 


78  INHERITANCE    IN   POULTRV. 

BODY  LACING. 

This  character  is  uot  fouud  in  the  Jungle  fowl,  but  may  have  been  derived 
from  the  penciling  of  the  Aseel-Malay  group.  In  male  hybrids  between 
the  Tosa  fowl  and  the  Dark  Brahma  it  occurs,  derived  from  the  latter  (p.  54). 
It  appears  to  be  dominant. 

PENCILING. 

This  is  an  ancient  feminine  characteristic,  best  marked  in  the  Aseel- Indian 
group  (p.  53).  It  is  found  particularly  well  developed  in  the  Dark  Brahma 
female.  In  the  female  hybrids  between  that  race  and  the  Tosa  fowl  penciling 
is  well  developed  ;  it  is  dominant. 

GENERAL  TOPICS  IN  INHERITANCE. 

UNIT  CH.\RACTERS. 

Taxouomic  descriptions  of  plants  and  animals  give  a  list  of  their  specific 
characteristics  (Merkmale,  caracteresu  These  comprise  for  the  most  part 
only  tha  external  characteristics,  but  a  similar  list  might  be  made  for  internal 
characteristics.  In  addition  to  specific  characteristics,  those  of  a  higher 
order  (such  as  generic,  etc. )  and  those  of  a  lower  order  (such  as  varietal)  may 
be  enumerated.  Such  characteristics  are,  in  first  approximation,  unit  char- 
acters. They  are  of  prime  importance,  because  the  whole  problem  of  evolution 
is  that  of  the  origin  and  significance  of  the  various  unit  characters  of  the 
body. 

The  theory  of  the  unit  character  is  associated  with  that  of  its  bearer  in 
inheritance.  Darwin  (1876)  and  later  de  Vries  (1889)  designated  as  such 
bearers  particles  of  the  nuclear  material  named  "  pan  genes."  "Changed 
numerical  relation  of  pangenes  is  the  basis  of  fluctiiating  variability ;  dis- 
placement (Umlagerung)  of  pangenes  in  the  nucleus  conditions  retrogressive 
and  degressive  mutations  ;  while  the  formation  of  new  kinds  of  pangenes  is 
necessary  to  the  explanation  of  progressive  mutations  "  (/.  c,  those  exhibit- 
ing altogether  new  characteristics). 

The  two  main  hypotheses  of  the  origin  of  unit  character  ire  that  of  de  Vries 
and  that  of  Weismann.  De  Vries  sets  forth  his  hypothesis  at  the  very  begin- 
ning of  his  great  work,  "  Die  Mutatioustheorie."  His  words  may  be  thus 
translated  : 

As  mutation  theory  I  designate  the  doctrine  that  the  characteristics  of  organisms  are 
built  up  of  units  that  are  sharply  separable  one  from  another.  These  units  can  be  united 
into  groups,  and  in  related  species  the  same  units  and  groups  recur.  Transitions,  such 
as  the  external  forms  of  plants  and  animals  exhibit  in  such  numbers,  exist  between  the 

units  as  little  as  between  the  molecules  of  chemistr}- In  the  realm  of  the  doctrine 

of  descent  this  principle  leads  to  the  conviction  that  species  have  proceeded  from  one 
another  not  continuously  but  by  steps  [nicht  fliessend,  aber  stufenweise].  Each  new  unit 
added  to  the  older  ones  constitutes  a  step  and  separates  the  new  form,  as  an  independent 

species,  sharply  and  fully  from  the  species  whence  it  arose Die  neue  Art  ist  somit 

mit  einem  Male  da  ;  sic  entsteht  aus  der  friiheren  ohne  sichtbare  Vorbereituug,  ohne 
Ubergange. 


GENERAL  TOPICS    IN   INHERITANCE.  79 

Weismana,  on  the  other  hand,  is  only  less  clear  in  expressing  his  hypoth- 
esis. He  accepts,  of  course,  the  idea  of  unit  characters,  each  of  which  is  rep- 
resented in  the  germ  cells  by  a  "determinant."  "We  called,"  he  says  (1904, 
I.  P-  369),  "  determinants  those  parts  of  the  cjerm- substance  which  determine 
an  '  hereditary  character '  of  the  body  ;  that  is,  whose  presence  in  the  germ 
determines  that  a  particular  part  of  the  body,  whether  it  consists  of  a  group 
of  cells,  a  single  cell,  or  a  part  of  a  cell,  shall  develop  in  a  specific  manner, 
and  whose  variations  cause  the  variations  of  these  particular  parts  alone. ' ' 
The  "  hereditary  parts  "  may  be  small  or  "  large  regions,  whole  cell  masses 
of  the  body,  which  in  all  probability  vary  only  en  bloc,  as,  for  instance,  the 
milliards  of  blood  cells  in  man,  the  hundreds  of  thousands  or  millions  of  cells 
in  the  liver  and  other  glandular  organs,  the  thousands  of  fibers  in  a  muscle, 
or  of  the  sinews  or  fascia,  the  cells  of  a  cartilage  or  a  bone,  and  so  on.  In 
all  these  cases  a  single  determinant,  or  at  least  a  few  in  the  germ  plasm,  may 
be  enough."  For  Weismann  (1904,  II,  p.  151)  the  ultimate  source  of  all 
hereditary  variations  is  the  variation  of  the  representatives  of  the  unit  char- 
acters in  the  germ  plasm.  "  If  I  mistake  not,"  he  says,  "  we  may  at  least 
say  so  much,  that  all  variations  are,  in  ultimate  instance,  quantitative  and 
that  they  depend  on  the  increase  or  decrease  of  the  vital  particles,  or  their 
constituents,  the  molecules What  appears  to  us  a  qualitative  varia- 
tion is,  in  reality,  nothing  more  than  a  greater  or  less  different  mingling  of 
the  constituents  which  make  up  the  higher  unit ;  an  unequal  increase  or 
decrease  of  these  constituents,  the  lower  units."  The  cell  changes  its  consti- 
tution when  the  proportion  of  its  component  parts  "  is  disturbed,  when,  for 
instance,  the  red  pigment  granules  which  were  formerly  present,  but  scarcely 
visible,  increase  so  that  the  cell  looks  red.  If  there  had  previously  been  no 
red  granules  present,  they  might  have  arisen  through  the  breaking  up  of 
certain  other  particles — of  protoplasm,  for  instance,  in  the  course  of  metab- 
olism —so  that,  among  other  substances,  red  granules  of  uric  acid  or  some 
other  red  stuff  were  produced.  In  this  case,  also,  the  qualitative  change 
would  depend  on  an  increase  or  decrease  of  certain  simpler  molecules  and 
atoms  constituting  the  protoplasm-molecule." 

In  criticism  of  the  foregoing  it  may  be  said  that  a  variation  in  the  number 
of  atoms  in  a  protoplasmic  molecule  is  certainly  also  a  qualitative  change — 
a  mutation.  The  only  real  dift'erence  between  Weismann  and  de  ^'■ries 
depends  on  the  extent  of  the  mutative  modification,  whether  progressive  or 
complete  from  the  beginning ;  but  this  is  a  real  difference,  for  the  latter 
view  is  required  by  the  theory  of  immutable  unit  characters.  The  former 
view  is  not  in  harmony  with  such  a  theory.  Conversely,  if  it  appears  that 
there  are  immutable  unit  characters,  then  the  theory  of  evolution  by  saltation 
is  necessary  ;  if  unit  characters  are  modifiable,  then  species  may  have  arisen 
gradually. 


8o  INHERITANCE    IN    POULTRY. 

The  result  of  the  breeding  experiments  described  herein  bears  upon  this 
discussion.  No  other  group,  I  imagine,  exhibits  so  many  characteristics  as 
poultr}'  ;  of  the  comb  alone  there  are  half  a  dozen  forms.  The  forms  of 
feathers  and  their  color  patterns  are  numerous.  These  forms  are  sharply 
marked  off  from  one  another  for  the  most  part  ;  moreover,  when  two  char- 
acteristics are  crossed  the  result  is  rarely  a  blend.  This  was  a  great  surprise 
to  me,  as  I  had  anticipated  that  blends  would  be  the  rule  ;  and,  overwhelmed 
by  the  facts,  I  embraced  at  once  the  theory-  of  immutable  characteristics. 

That  there  are  unit  characters  in  poultry  can  not  be  doubted.  When  single 
and  V  comb  are  crossed  and  progeny  obtained  all  with  a  Y  comb,  how  con- 
vincingly do  the  second  hybrids  reproduce  the  single  comb  in  some  individuals 
and  the  V  comb  in  others  !  Though  the  cerebral  hernia  and  its  associated 
great  crest  may  disappear  in  the  first  generation  of  hybrids,  how  beautifully 
do  they  reappear  in  one-fourth  of  the  offspring  of  such  hybrids  !  How  in- 
structive is  it  to  see  perfectly  plain  feathered  offspring  arising  from  a  frizzled 
pair,  or  in  a  Black  Minorca  X  Dark  Brahma  white-laced  hackles  appearing 
in  an  otherwise  dead-black  plumage  !  Truly  we  may  hope,  as  in  chemistry, 
to  make  various  kinds  of  molecules  by  the  proper  admixture  of  our  atoms — 
the  characteristics.  Even  in  man  such  non-blending  characteristics  are  evi- 
dent. One  of  the  most  famous  is  the  Hapsburg  lip  or  chin,  which  from  the 
fifteenth  century  has  persisted  to  the  present  day  despite  infusion  of  new 
blood  during  fifteen  generations.*  Another  striking  case  is  that  of  hypo- 
phalangia  in  man,  described  by  Farabee  (1905).  In  the  four  or  five  gener- 
ations studied,  there  has,  he  states,  "never  been  a  single  instance  of  partial 
inheritance,  but  in  all  cases  all  extremities  have  been  aiTected  in  precisely 
the  same  way." 

While  admitting,  thus,  the  reality  of  unit  characters,  the  further  study  of 
the  evidence  of  hybridization  in  poultry  has  led  me  away  from  the  conception 
that  they  are  rigid  and  immutable  as  atoms  are,  which  may  be  combined 
and  recombined  in  various  way  and  ahvays  come  out  of  the  process  in  their 
pristine  purity.  This  is  by  no  means  the  case.  Very  frequently,  if  not 
always,  the  character  that  has  been  once  crossed  has  been  aflfected  by  its 
opposite  with  which  it  was  mated  and  whose  place  it  has  taken  in  the  hybrid. 
It  may  be  extracted  therefrom  to  use  in  a  new  combination,  but  it  will  be 
found  to  be  altered.  This  we  have  seen  to  be  true  for  almost  every  char- 
acteristic sufficiently  studied — for  the  com^b  form,  the  nostril  form,  cerebral 
hernia,  crest,  muff,  tail  length,  vulture  hock,  foot- feathering,  foot  color,  ear- 
lobe,  and  both  general  and  special  plumage  color.  Everywhere  unit  char- 
acters are  changed  by  hybridizing. 

How  does  this  fact  bear  on  the  rival  theories  of  evolution  ?  It  has  an  im- 
portant bearing  on  them.     It  is  not  in  accord  with  the  statements  of  de  Vries 


Cf.  V .  A.  Woods,  1902-03. 


GENERAL  TOPICS   IN    INHERITANCE.  8 1 

quoted  above  :  "  The  characteristics  of  organisms  are  built  up  of  units  that 
are  sharply  separable  one  from  another,"  and  "Transitions  exist  between 
the  unit  as  little  as  between  the  molecules."  Single  comb  is  one  unit  and 
pea  comb  is  a  different  unit,  but  they  are  not  sharply  separable.  Crest  and 
no  crest  are  units,  but  they  run  into  each  other  in  hybridizing.  Unit  char- 
acters may  show  transitions,  and,  if  so,  they  viay  have  originated  gradually, 
so  far  as  I  see.     It  does  not  follow  that  they  must  have  originated  gradually. 

ai.te;rnative,  particulate  (mosaic),  and  blending  inheritance. 

Doubtless  Darwin's  statement  that  crossed  characters  usually  blend  is 
still  the  prevalent  view.  Much  if  not  most  biometric  work  in  heredity  has 
been  made  on  this  basal  assumption.  I  may  say  that  I  began  my  experi- 
ments prejudiced  in  favor  of  this  view\ 

The  results  that  have  been  recorded  in  the  foregoing  pages  indicate  that 
probably  in  general  typical  blending  of  characters  is  rare.  Excepting  char- 
acters like  general  form  of  the  body,  which  are  doubtless  not  units,  but 
complex.  I  have,  indeed,  seen  no  single  case  of  a  typical  blend.  A  fusion 
of  characters  is  a  rather  rare  phenomenon.  Human  skin  color  is  the  one 
striking  case.  One  can  but  wish  we  had  more  careful  data  on  inheritance 
of  human  skin  color  in  successive  generations.  Other  human  characteristics 
show  alternative  inheritance.  This  is  strikingly  true  in  Farabee's  family  of 
hypodactyls  cited  above.  It  is  said  to  be  true  of  eye  color  and  probably 
of  the  states  of  general  pigmentation  known  as  blonde  and  brunette. 

The  following  characters  of  poultry  show  alternative  inheritance  : 

Comb  form.  Uropygium.  Earlobe  color. 

Nostril  form.  Tail  length.  General  plumage  color 

Cerebral  hernia.  Vulture  hock.  (sometimes). 

Crest.  Booting.  Color  of  hackles. 

Muff.  Extra  toe.  Wing  bar. 

Beard.  Color  of  mandible  Shafting. 

Frizzling.  and  foot.  Body  lacing. 

Silkiness.  Iris  color.  Penciling. 

The  following  characteristics  show  particulate  inheritance  : 

Iris  color  (sometimes?). 

White  and  black,  producing  barring  (Series  VI,  VII,  IX,  XII). 
White  and  black,  producing  blue  (fig.  54)  (a  fine  mosaic  of  white  and 
black). 

It  is  too  early  yet  to  interpret  the  cases  of  particulate  inheritance.  It  is  a 
striking  fact  that,  excepting  the  Tosa  X  White  Cochin  cross,  all  my  barred 
birds  reared  to  maturity  had  the  White  Leghorn  Bantams  as  mother  or 
father.  Now,  as  repeatedly  observed,  these  bantams  were  heterogametous. 
It  is  possible  that  they  contain  barred  blood  in  the  "fixed"  condition. 
Aside  from  the  fact  that  they  throw  a  certain  proportion  of  barred  birds,  this 
conclusion  gains  support  from  the  fact  that  the  wing  coverts  of  the  male  are 
6 


82  INHERITANCE    IN    POULTRY. 

obscurely  barred  with  dusty  bands,  althougli,  on  the  other  hand,  this  barring 
may  be  merely  the  badge  of  hetero/.ygotism.  It  is  possible,  therefore,  that 
the  barring  in  the  plumage  of  the  White  Leghorn  Bantams  is  transmitted  as 
an  alternative  characteristic.  The  case  of  the  barred  descendants  of  the 
Tosa  X  White  Cochin  is  more  difficult.  I  am  not  yet  prepared  to  go  so  far 
as  Correns  (1905"*,  p.  13,  note)  when  he  says:  "Wo  Mosaikbildung  als 
Regel  bei  einem  Bastard  auftritt,  war  sie  scbon  in  einem  der  Eltern  oder  in 
beiden,  aktiv  oder  latent,  vorhanden," 

Naturally,  attention  was  directed  chiefly  toward  evident  qualitatively 
marked  characteristics.  Such  do  not  blend.  The  fact  that  for  the  most 
part  a  characteristic  does  not  blend  when  crossed  with  its  allelomorph  is  of 
the  highest  importance  for  the  theory  of  evolution.  If  blending  were  uni- 
versal a  new  characteristic  must  inevitably  become  quickly  swamped  by 
intercrossing  with  the  parental  characteristic.  Since  the  new  quality  does 
not  blend,  it  need  not  be  swamped,  even  when  there  is  no  special  isolation. 

INHERITANCE  OF  SPECIFIC  VS.  VARIETAL  CHAR.\CTERISTICS. 

A  distinction  between  specific  and  varietal  characteristics  is  made  by 
Nageli  (1884,  p.  247)  and  by  de  Vries  (1902,  p.  141  ;  1905,  p.  141).  Fol- 
lowing de  Vries,  a  specific  characteristic  is  a  wholly  novel  one  acquired  by  the 
race — one  which  stamps  its  possessor  as  an  elementary  species,  A  varietal 
characteristic  is  sometimes  positive  (/.  <?.,  additional),  in  which  case  it  is 
found  also  in  closely  allied  species,  and  may  be  regarded  as  the  becoming 
patent  of  a  characteristic  all  the  time  latent  in  the  variety.  It  is,  on  the 
other  hand,  sometimes  negative,  this  condition  being  marked  by  the  disap- 
pearance (becoming  latent)  of  a  characteristic  patent  in  the  ancestral  species. 
Specific  and  varietal  characteristics  are  thought  by  de  Vries  to  be  inherited 
very  differently.  When  two  elementary  species  are  crossed  the  character- 
istics of  both  parents  appear,  fully  developed,  side  by  side  ;  Mendel's  law  is 
not  follov/ed.  When  a  species  is  cro-ssed  with  a  variety  a  Mendelian  result 
is  obtained  and  the  patent  characteristic  is  dominant  over  the  latent. 

Let  us  now  see  in  how  far  the  results  gained  in  breeding  poultry  accord 
with  de  Vries's  law.  It  is  not  easy  to  make  the  classification  in  an  unpreju- 
diced way  ;  an  attempt,  however,  will  be  made. 

First,  the  comb  is  a  specific  characteristic  of  the  genus  Gallus.  It  is  absent 
in  other  Gallinse.  Also  pea  comb  and  rose  comb  are  each  wholly  new,  posi- 
tive variations  from  the  primitive  single  comb.  Muff  and  beard  seem  to  be 
novel ;  so  also  the  long  tail  of  the  Tosa  fowl,  the  extra  toe,  and  the  melanic 
feet  and  beak. 

Clear  cases  of  negative  variations  are  :  Loss  of  the  nasal  process  of  inter- 
maxillary and  consequent  high  nostril ;  failure  of  cerebral  plate  to  close  and 
consequent  cerebral  hernia  ;  loss  of  uropygium  ;  loss  of  red  and  black  pig- 
ment in  feathers  (albinism,  partial  or  complete)  ;  loss  of  dark  pigment  in 
crest  feathers  ;  loss  of  wing  bar  ;  loss  of  primitive  shafting. 


GENERAL   TOPICS   IN    INHERITANCE. 


83 


Now,  by  hypothesis  we  should  expect  a  difference  in  inheritance  in  these 
characteristics  as  indicated  below  : 


Expected  non-Mendelian, 

Expected  Mendelian, 

1.  Pea  and  rose  comb  vs.  single  comb. 

2.  Muflf  and  beard  vs.  plain  head. 

3.  Long  tail  vs.  normal. 

4.  Extra  toe  vs.  normal. 

5.  Melanic  feet  and  beak  z^s.  willow  or 

yellow. 

1.  High  nostril  vs.  low. 

2.  Cerebral  hernia  z'S.  normal. 

3.  Taillessness  vs.  normal  tail. 

4.  Albinism  in  plumage  I's.  pigment. 

5.  Absence  of  wing  bar  z's.  presence. 

6.  Absence  of  shafting  vs.  presence. 

Of  the  five  cases  where,  on  de  Vries's  theory,  we  should  expect  non-Men- 
delian results,  No.  4  is  apparently  not  Mendelian,  No.  5  gives  often  a 
mixture  of  characters,  Nos.  i  and  2  apparently  give  true  Mendelian  domi- 
nance and  recessiveness.  No.  3  is  still  doubtful.  Of  the  six  cases  in  which 
a  Mendelian  inheritance  is  looked  for,  we  certainly  find  it  in  three  cases  and 
less  certainly  in  the  others.  On  the  whole,  there  is  a  slight  but  not  a  striking 
difference  in  transmission  between  the  two  sets  of  characteristics,  and  I  can 
only  conclude  that  for  poultry,  so  far  as  I  can  see  at  present,  de  Vries's 
formula  does  not  hold  universally. 

INHERITANCE   OF   POSITIVE   VS.    NEGATIVE   VARIETAT^   CHARACTERISTICS. 

According  to  de  Vries,  when  an  individual  hiving  a  certain  characteristic 
patent  is  crossed  with  one  in  which  it  is  latent  the  patent  characteristic  is 
dominant,  the  latent  recessive.     Do  results  with  poultry  confirm  this  law  ? 

In  the  following  table  the  patent  characteristic  is  given  in  the  left-hand 
column  and  the  dominant  characteristic  in  italics  : 


Patent. 

Latent. 

1.  Nasal  process  of  premaxillary,  nai'row 

nostril. 

2.  Closure  of  cerebrum  completed  ;  plain 

head. 
X    Cre'it  •  black  crest  feathers  

High  nostril. 

Failure  of  cerebrum   to  close  ;    cerebral 

hernia. 
Smooth  head  ;  white  crest  feathers. 
Interrupted  development  of  the  feather  ; 

silky  feather. 
Taillessness. 
Albinism  in  plumage. 
Uniformly  colored  wing. 
Plain  feather. 

4.  Complete  development  of  the  feather .  . 

5.  Tail 

fi    Piornented  nlumafe        

7.  Red  zvijig  bar 

8.  Shafting 

Of  the  foregoing  eight  characters,  seven  clearly  follow  the  law  that  patent 
characteristics  dominate  over  latent.  No.  6  is  a  clear  exception,  for  since 
all  the  wild  Galliuae  are  deeply  pigmented  birds  it  can  hardly  be  doubted 
that  white  is  a  negative  variation  in  which  color  is  latent.  However,  the 
exception  (No.  6)  is  not  universal,  for  white  plumage  does  not  always  domi- 


84 


INHERITANCE    IN    POULTRY. 


nate  over  pigmented  plumage.  It  appears,  then,  that  the  patent  character 
is,  in  general,  but  with  some  exceptions,  dominant  over  the  corresponding 
latent  character. 

INHERITANCE  OF  OLD  VS.  NEW  CHAR.\CTERISTICS. 

Standfuss  (1896,  p.  11 1 ),  as  a  result  of  his  hybridization  of  moths,  concluded 
that  hybrids  resemble  the  older  species.  De  Vries  (1902,  pp.  33-42,  and 
1905,  pp.  280,  281)  cites  several  instances  of  the  prepotency  of  the  phyloge- 
netically  older  characteristic.  Bateson  and  Saunders  (1902,  p.  137),  how- 
ever, point  out  that  younger  characteristics  sometimes  dominate,  and  cite 
pea  and  rose  comb,  extra  toe,  and  the  polled  condition  of  cattle  as  examples. 
Correns  (1905,  p.  463  et  seq.)  describes  a  case  of  petaloid  calyx — a  new 
characteristic — which  is  dominant  over  the  normal  form.  Correns  (1905'^, 
p.  13),  indeed,  concludes  that  in  general  the  phylogenetically  more  advanced 
characteristic — the  later  originated,  yoioiger  characteristic — dominates. 

Let  us  see  what  evidence  poultry  hybrids  have  to  offer  bearing  on  this  point. 


Old  characteristics. 

New  characteristics. 

Old  characteristics. 

New  characteristics. 

I.  Single  comb 

Rose  comb. 

II.  White  skin 

Black  skin. 

2.  Lozu  7iosiril 

High  nostril. 

12.  Red  iris.i   

Black  iris. 

3.  No  hernia 

Hernia. 

13.  Red  ear  lobe 

White  earlobe. 

4.  Plain  head 

Crest. 

14    Pigmented. .  . 

White  (sometimes 

5.  No  tnnffling 

Mtifflino;. 

dominates). 

6.  Plain  feathers. . . 

Frizzled  feathers. 

15.  Red  pigmented. 

Black  ;  no  r-ed. 

7.  Plain  feathers .. . 

Silkv  feathers. 

1  16.  Black  head 

White  head. 

8.   Tailed  (?) 

Non-tailed. 

17.   Hackle  lacing.  . 

Solid  black. 

9.  Tail  featliers  lim- 

Tail unlimited. 

18.  Red  iving  bar. . 

No  wing  bar. 

ited  in  growth . 

19,  Shafting 

No  shafting. 

10.  Four  toes 

Five  toes. 

20.  Penciling 

No  penciling. 

This  table  shows  that  of  nineteen  characteristics  (No.  10  being  left  out  of 
consideration),  nine  old  ones  are  dominant  and  ten  new  ones.  Clearly,  dom- 
inance of  characteiistics  in  poultry  is  not  determined  by  the  age  of  the 
characteristic. 

DOMINANCE  AND  RECESSIVENESS. 

Mendelian  dominance  and  recessiveness  with  segregation  of  characteristics 
in  the  gametes  are  not  universal  concomitants  of  hybridization.  Mendel  knew 
it  (Correns,  1905^)  ;  de  Vries  founds  his  system  on  the  fact  ;  Correns  lays 
stress  on  it  ;  Bateson  and  Saunders  (1902,  p.  152)  recognize  it,  but  consider 
the  exceptions  insufficiently  known.  The  characteristics  that  I  have  cros.sed 
show  always  segregation  excepting  extra  toe  and  perhaps  also  melanic  foot 
and  beak  color.  These  are  among  the  positive  variations  of  de  Vries,  which, 
in  accordance  with  his  sj^stem,  we  should  not  expect  to  *'  mendelize."  As 
stated,  other  positive  variations,  however  (pea  comb  and  muffj,  .seem  to 
mendelize. 


GENERAL   TOPICS    IN    INHERITANCE.  85 

Of  the  varietal  characteristics,  the  positive  or  patent  characteristics  almost 
always  are  dominant,  white  plumage  forming  an  occasional  exception.  On 
the  other  hand,  phylogen^tically  old  characters  are  not  more  apt  to  be  domi- 
nant than  "new"  ones.  Some  evident  sports,  such  as  crest,  frizzling  of 
feathers,  unlimited  growth  of  tail,  and  black  skin  (of  Silky),  are  dominant. 
Other  sports — hernia,  shortened  premaxillary,  silkiness,  and  rumplessness — 
are  recessive ;  the  novelty  or  antiquity  of  the  characteristic  has  nothing  to 
do  with  its  dominance.  Dominance  of  a  character  in  hybridization  is  deter- 
mined by  the  same  causes  as  determine  the  appearance  in  ihe  race  of  a  posi- 
tive variation.  A  progressive  variation,  one  which  means  a  further  stage  in 
ontogeny,  will  be  dominant;  a  variation  that  is  due  to  abbreviation  of  the 
ontogenetic  process,  which  depends  on  something  having  dropped  out,  will 
be  recessive. 

This  conclusion,  however  satisfactory,  must  be  regarded  as  tentative.  It 
is  doubtful  if  it  is  of  general  validity  ;  for  while  long  tail  and  crest  feathers 
are  dominant  in  poultry,  long  hair  (equally  due  to  prolonged  life  of  the  fol- 
licle) is  recessive  in  mammals  (Castle,  1903  ;  1905,  pp.  64-67,  73-74;  Hurst, 
1904).  White  is  usually  recessive  to  pigment  in  flowers  and  mammals,  but 
it  is  usually  dominant  over  pigment  in  poultry.  It  is  still  too  early  to  regard 
the  conclusions  expressed  in  the  last  paragraph  as  anything  but  an  hypothesis. 

While  dominance  and  recessiveness  are  typically  found  in  Mendelian  in- 
heritance, yet  they  may  be  absent  even  in  cases  when  segregation  of  charac- 
teristics occurs  in  the  second  hybrid  generation.  Thus,  the  barred  offspring 
of  the  black-and-red  Tosa  fowl  and  the  white  Cochin  throw  in  the  F,  gener- 
ation 25  per  cent  black  and  red  and  25  per  cent  white,  but  the  remainder, 
like  all  of  Fj,  is  barred  with  white,  and  no  one  can  saj^  which  plumage  color 
is  dominant.  The  same  is  true  of  some  black-and-white  barred  hybrids.  It 
is  also  true  of  hybrids  between  single  and  V  comb.  The  phenomena  of  domi- 
nance and  recessiveness  do  not  always  accompany  segregation. 

Another  modification  of  the  law  of  dominance  and  recessiveness  must  be 
recognized,  namely,  that  they  are  by  no  means  always  complete.  Even  in 
the  first  hybrid  generation  the  dominant  characteristic  is  more  or  less  inter- 
mediate. The  antagonistic  characteristics  a  and  a'  of  the  two  parent  types 
are  not  only  united  in  the  zygote,  but  they  pass  in  the  development  of  the  or- 
ganism into  all  the  tissues  of  the  body,  and  particularly  into  the  cells  out 
of  which  the  organ  A  is  developed.  The  dominant  characteristic,  a,  and 
the  recessive  characteristic,  a' ,  each  works  to  determine  the  qualit)''  of  the 
organ  A.  \i  a  dominates,  it  is  because  it  is  more  active  than  a' .  It  does 
not  dominate  by  excluding  a' .  Sometimes,  as  in  the  case  of  barred  feathers, 
it  appears  that  a  and  a'  in  ontogeny  alternate  in  their  activities.  The  cells 
of  a  certain  zone  of  the  feather  manufacture  only  black  pigment  ;  in  the  next 
zone  black  is  wanting  ;  then  comes  a  zone  of  black,  and  so  on,  in  many  repe- 
titions. Dominance  as  contrasted  with  recessiveness  is  a  matter  of  degree 
and  not  of  kind. 


86  INHERITANCE   IN    POULTRY. 

Various  authors  refer  to  the  imperfection  of  the  dominant  or  recessive 
characteristic  in  the  hybrid.     Bateson  and  Saunders  (1902,  p.  23)  say  : 

Although  the  oflfspriug  resulting  from  a  cross  between  any  two  of  the  forms  (of  Datura) 
employed  is  usually  indistinguishable  from  the  type  which  is  dominant  as  regards  the 
particular  character  crossed,  yet  in  other  cases  th"::  intensity  of  a  dominant  character  may 
be  more  or  less  diminished  either  in  particular  individuals  or  in  particular  parts  of  one 
individual. 

Hurst  (1905,  pp.  145-154)  records  many  cases  of  imperfect  dominance  in 
poultry  and  estimates  the  incomplete  dominants  to  be  twice  as  numerous  as 
the  complete  dominants. 

DKPHNDKNCE  OK  DOMINANCE  ON  THE   RACES  CROSSED. 

Is  one  of  a  pair  of  allelomorphs  that  shows  itself  dominant  when  varieties 
A  and  B  are  crossed  likewise  dominant  when  any  other  varieties,  M  and  A^, 
are  crossed,  or  is  the  relative  potency  of  the  allelomorphs  dependent  upon 
the  varieties  in  which  they  happen  to  reside  ? 

Data  for  an  answer  to  this  question  are  to  be  found  in  the  experiments  where 
the  same  pair  of  allelomorphs  were  crossed ,  using  different  varieties.  We  may 
except  from  this  list  the  Minorca  x  Polish  and  the  lyCghorn  x  Houdan  crosses, 
as  the  races  involved  are  very  closely  related.  The  following  allelomorphs 
remain  for  consideration  : 

(i)  Crest  vs.  crestlessness.  (6)  Extra  vs.  normal  toes. 

(2)  Silkiness  vs.  non-silkiness.  {"])  Black  vs.  white  skin. 

(3)  Rumplessness  vs.  tail.  (8)  Black  vs.  yellow  beak. 

(4)  Vulture  hock  vs.  plain  hock.  (9)  White  vs.  dark  plumage. 

(5)  Boot  vs.  clean  foot. 

Crest. — This  is  dominant  when  Polish  or  Houdan  is  cro.ssed  with  the 
Mediterranean  breeds  and  when  the  Silky  is  crossed  with  the  Frizzle  or  with 
the  Jungle  fowl.  Crest  is  uniformly  dominant  over  crestlessness,  no  matter 
which  of  these  races  are  used. 

Silkiness  is  reces-sive  to  non-silkiness  when  crossed  with  Frizzle  or  the 
Jungle  fowl.     Non-silkiness  is  probably  always  dominant. 

Rumplessness  in  a  Game  fowl  was  recessive  to  the  tailed  condition  of  Leg- 
horn, Cochin,  Frizzle,  and  Nankin.  The  tailed  condition  seems  always  to 
dominate. 

V21I litre  hock  is  recessive  when  an  Asiatic  race  is  crossed  with  any  Med- 
iterranean breed  or  a  Game,  and  probably,  in  general,  plain  hock  dominates. 

Booting  is  dominant  when  the  booted  form  is  the  mother,  no  matter  what 
the  race.  Booting  is  much  reduced  and  sometimes  altogether  absent  in  the 
first  generation  of  hybrids  when  it  is  deriv^ed  from  the  father.  Inheritance 
of  booting  is  independent  of  race  but  not  of  sex  (p.  38). 

Extra  toe  seems  not  to  Mendelize.  The  excess  of  extra  toes  in  the  first 
hybrid  generation  holds  for  all  the  races  crossed  and  is  probably  independent 
of  race. 


GENERAL,   TOPICS   IN    INHERITANCE.  87 

Black  skill  of  the  Silky  dominates  over  the  colorless  skin  of  the  Frizzle 
and  of  the  Jungle.     It  probably  dominates  throughout. 

Yellow  vs.  black  beak  and  foot  color. — Yellow  of  the  White  Leghorn  domi- 
nates over  black  of  the  Minorca,  but  yellow  of  the  Dark  Brahma  is  domi- 
nated by  the  Minorca.  Here  yellow  behaves  differently,  according  as  it  is 
in  the  Leghorn  or  Dark  Brahma  race.  It  is  quite  possible  that  the  yellow 
is  not  identical  in  the  two  groups,  but  that,  while  it  is  ancestral  in  the  Dark 
Brahma,  it  is  secondary  and  a  progressive  character  in  the  Leghorn.  The 
lack  of  uniformity  in  dominance  of  yellow  may  be  due  to  essential  dissimi- 
larity of  the  character  in  different  races. 

White  vs.  dark  plumage. — Aside  from  cases  of  barring  and  Andalusian 
coloration,  white  usually  dominates  over  dark  plumage.  This  is  true  in  all 
cases  where  White  Leghorn  is  employed  as  white  race,  whether  the  other 
race  is  Game,  Dark  Brahma,  Houdan,  or  Minorca.  When  the  Silky  is  used 
as  the  white  race  white  is  sometimes  recessive  (fig.  53),  but  it  must  be  ac- 
knowledged that  the  dark  parents  were  not  the  same  as  were  used  with  the 
Leghorn,  but  were  a  Game,  Frizzle,  and  Jungle  fowl  ;  consequently  the 
results  in  the  two  series  are  not  strictly  comparable.  However,  Darwin 
found  the  white  of  the  Silky  recessive  to  the  black  of  the  Minorca.  It  is 
hardly  conceivable  that  the  white  of  the  Silky  is  different  from  that  of  the 
Leghorn ;  so  it  must  be  concluded  that  white  inherited  as  a  solid  color  is 
sometimes  dominant  and  sometimes  recessive,  depending  on  the  race  in  which 
it  inheres. 

Summarizing  the  foregoing  evidence,  it  appears,  first,  that  (except  in 
certain  obviously  complex  color  characters)  when  one  of  a  pair  of  allelo- 
morphs is  dominant  it  is  so  regardless  of  the  races  crossed.  This  shows 
that  dominance  and  recessiveness  depend  upon  a  relation  of  the  character- 
istics per  se  and  not  upon  any  relation  of  the  races  into  which  they  have 
been  introduced.  This  is  in  accord  with  the  conclusion  reached  above,  that 
dominance  is  determined  by  the:  positive  nature  of  the  characteristic  (p.  84). 

PREPOTENCY  AND  DOMINANCE. 

Prepotency  was  a  much  used  and  probably  abused  term  in  the  period  pre- 
ceding the  revival  of  Mendelism.  In  the  new  era  all  of  the  old  terms  have 
been  subjected  to  reexamination  as  to  their  significance.  Bateson  and  Saun- 
ders (1902,  p.  121)  use  the  term  "as signifying  determination  of  dominance," 
i.  e.,  whether  the  normally  dominant  or  the  normally  recessive  character 
shall  be  in  any  case  actually  dominant.  Castle  (1905,  pp.  58-64)  shows  that 
although  rough  coat  is  dominant  over  smooth  coat,  a  few  smooth-coated 
mothers  will,  when  crossed  with  rough  males,  produce  partial-rough  young. 
The  normally  recessive  character  here  partially  dominates.  In  my  own 
experiments  the  most  remarkable  case  of  dominance  is  exhibited  by  a  gamete 
from  the  maternal  side  that  produced  the  Houdan  x  White  Leghorn  hybrid 


88  INHERITANCE   IN   POULTRY. 

No.  3S6  9  ;  for  this  hybrid  has  a  high  nostril  and  a  pair  of  papillae  like 
the  Houdan  mother,  both  of  which  characters  are  recessive.  Out  of  41  in- 
dividuals No.  386  is  the  only  one  that  exhibits  them.  It  appears,  then,  that 
' '  prepotency  ' '  in  its  modern  sense  can  not  be  neglected. 

HYBRID    FORMS. 

It  sometimes  happens  when  two  dissimilar  characteristics  are  crossed  that 
neither  appears  in  the  offspring,  but  they  are  replaced  by  a  new  character. 
This  fact  has  been  long  knowm.  Mendel  obtained  such  hybrid  forms  {cj., 
Correns,  1905,  p.  232).  Several  cases  are  cited  by  Focke  (1881,  pp.  473,  474). 
He  refers  particularly  to  the  blue  hybrid  of  the  white  Datura  Jcrox  crossed 
with  the  likewise  white  D.  lacvis  and  D.  stranimonium  Bertolonii. 

As  a  result  of  more  recent  work  it  appears  probable  that  hjbrid  forms  are 
of  two  kinds.  First,  such  as  are  atavistic  or  due  to  the  becoming  patent  of 
a  latent  characteristic  ;  *  and,  second,  such  as  are  due  to  a  particulate  inher- 
itance of  the  two  characteristics  crossed.  In  the  latter  case  all  that  is  novel 
in  the  hybrid  is  the  replacement  of  either  single  character  by  a  combination 
of  characteristics. 

Atavistic  hybrid  forms  have  been  carefully  investigated  of  late,  especially 
by  Correns  (1902)  and  Cuenot  (1903),  who  have  applied  a  method  of  inter- 
pretation to  particular  cases.  When  albino  mice  are  crossed  inter  se  they 
produce  only  albinos.  But  if  such  an  albino  is  crossed  with  a  pigmented 
(<?.  g.,  a  black)  mouse  its  latent  pigment  appears  and  the  offspring  may  be 
all  gray,  or  perhaps  yellow  and  gray  or  yellow  and  black.  The  same  holds 
exactly  true  for  albino  rabbits,  as  Hurst  (1905,  pp.  306-310)  has  shown. 
Cuenot's  interpretation  depends  on  the  principle  that  pigments  result  from 
the  action  of  an  oxidizing  diastase  (tryosinase)  upon  a  chromogenic  sub- 
stance. Both  of  these  elements  are  present  in  a  pigmented  mouse,  but  he 
assumes  the  chromogenic  substance  alone  is  present  in  the  albino.  The  sperm 
from  the  pigmented  male  brings  to  the  egg  of  an  albino  the  diastase  necessary 
to  the  production  of  pigment  in  the  offspring.  Correns  (1905")  finds  that 
the  hybrid  of  Mirabilis  jalapa  alba  (white  flowers)  and  M.  jalapa  gilva  (yel- 
low flowers)  has  rose-colored  flowers  that  are,  moreover,  striped  with  red. 
His  experiments  lead  to  the  conclusion  that  the  alba  variety  forms  no  pig- 
ment, but  does  produce  a  pigment-changing  (reddening)  enzyme.  t\x^ gilva 
variety  forms  pigment,  but  not  the  reddening  enzyme.  When  alba  sperm 
unites  with  the  gilva  egg  the  pigment  of  the  latter,  under  the  influence  of 
the  reddening  enzyme,  becomes  rose.  Similarly  with  striping.  There  is 
evidence  that  this  is  only  partly  latent  in  alba  and  completely  latent  \n  gilva. 
Now  if  we  assume  a  factor  that  permits  the  development  of  the  striping 
determinant  to  be  active  in  gilva  but  to  be  latent  in  alba,  the  imperfect 

*Tschermak  (1904,  p.  95)  would  add  as  another  kind  that  in  which  an  originally  patent 
character  becomes  latent. 


GENERAL   TOPICS    IN   INHERITANCE. 


89 


development  in  alba  of  the  striping  determinant  is  accounted  for.  When  the 
sperm  of  gilva,  bringing  the  active  principle  for  striping,  fertilizes  the  egg 
of  alba  with  its  striping  determinant,  the  striping  makes  its  full  appearance. 
These  two  or  three  examples  from  both  plant  and  animals  indicate  a  method 
of  explaining  hybrid  forms  that  is  probably  of  wide  applicability. 

Are  the  hybrid  forms  of  poultry  to  be  explained  on  the  atavistic  or  the 
particulate  inheritance  theory?  Take  first  the  case  of  barring.  Three 
tests  can  be  applied  :  First,  inherent  probability  from  the  ancestr>'  of  the  fowl 
crossed  ;  second,  general  distribution  of  barring  among  the  offspring  ;  third, 
proportion  of  different  forms  of  plumage  pattern  in  generations  beyond  the 
first.  The  cross  between  Tosa  fowl  and  White  Cochin  gave  barred  birds. 
If  the  barring  were  latent  it  must  have  lain  in  the  Cochins — the  form  without 
visible  pattern.  It  is  fairly  certain  that  neither  of  the  ancestors  of  domestic 
fowl  was  barred  ;  hence  if  the  barring  determinant  existed  in  the  Cochin 
bantam  it  must  have  been  introduced  by  a  recent  cross.  Bantamizing  of 
Cochins  is  effected  by  crossing  with  some  bantam  race,  but  until  recently 
no  barred  bantams  have  been  created.  It  is  therefore  highly  improbable 
that  a  barred  bird  was  used  to  bantamize  the  Cochins.  While  it  is  possible, 
it  is  improbable  that  the  White  Cochin  contained  a  barred  determinant. 
Second,  barred  races  have  the  two  sexes  equally  barred,  but  our  hybrids 
are  barred  in  the  male  only  ;  consequently  barring  here  acts  like  a  neomorph. 
Third,  on  the  theory  of  atavism  we  should  expect  to  get  in  the  second  hybrid 
generation  : 


Coloration  of  second  generation. 

Atavism       Particulate 
theory.           theorj'. 

Actual. 

White 

Pigmented  and  barred 

Per  cent. 
25.00 
56  25 
18.75 

Per  cent. 
25 
50 
25 

Per  cent. 
28 
48 
24 

Pigmented  and  not  barred 

The  actual  proportions  of  the  three  types  accord  much  better  with  the 
particulate  inheritance  theory  than  with  that  of  atavism,  but  the  total  number 
of  offspring  is  insufficient  to  give  certainty.  It  may  be  concluded  that  while 
the  evidence  does  not  exclude  the  atavism  theory  of  the  cropping  out  of 
barring,  it  favors  the  theory  of  particulate  inheritance. 

The  case  of  the  hybrid  between  single  and  V  comb  rests  on  more  extensive 
data.  These  are  set  forth  on  pages  10-12,  and  are  less  favorable  to  the  ata- 
vistic theory  than  to  the  particulate  theory. 

The  other  heterozygous  forms  have  been  less  carefully  studied.  They  are 
the  blue,  Andalusian  (fig.  54,  pi.  xvii),  plumage  color  resulting  from  a 
white  and  a  black  crossed,  and  the  case  of  the  down  of  the  hybrid  Minorca  x 
Dark  Brahma  chicks.  This  is  black  like  the  Minorca,  but  lacks  the  white 
of  the  chicks  both  of  that  race  and  of  the  Dark  Brahma.     The  Andalusian 


90  INHERITANCE    IN    POULTRY. 

hreed  has  been  discussed  by  Bateson  and  Punnett  (1905,  p.  126),  and  they 
find,  what  is  the  universal  testimony  of  breeders,  that  (as  stated  also  at  page 
76)  the  blues  bred  inter  se  produce  some  white  and  some  blacks,  but  still 
more  blues.  Until  more  complete  statistics  have  been  gained  on  the  pro- 
portions of  colors  in  the  offspring,  the  interpretation  of  blue  must  remain 
uncertain. 

Hybrid  forms  are,  then,  frequently  cases  of  particulate  inheritance  in 
which  the  hybrid  gametes  are  not  mosaic  ;  consequently  whenever  ' '  pure  ' ' 
offspring  are  produced,  as  in  Fj,  these  reassume  the  character  of  the  pure 
race.  In  some  cases,  as  in  the  cuckoo  Dorking  and  the  Dominique  (from 
which  our  barred  Plymouth  Rock  has  been  derived),  the  heterozygous  form 
of  barred  plumage  has  become  fixed,  so  that  only  barred  offspring  are  pro- 
duced. A  mosaic  gamete  has  been  created.  The  blue  coloration  has  never 
yet  been  fixed  as  a  permanent  hybrid  form.  The  method  of  fixing  a  hj-brid 
form  is  urgently  in  need  of  investigation. 

REVERSION. 

This  term  has  been  used  rather  loosely  in  the  past  for  the  appearance  in 
hybrids  of  characteristics  not  visible  in  the  immediate  parents  of  the  hybrids 
and  often  belonging  to  remote  ancestors.  Darwin  (1876)  made  much  use 
of  this  term  in  describing  his  results.  He  believed  that  the  occurrence  of 
"  reversion  "  gave  a  useful  key  to  ancestry.  It  is  worth  while  to  consider 
his  observations  and  experiments.  He  mentions  the  fact  that  "  purely  bred 
Game,  Malay,  Cochin, Dorking,  Bantam,  and Silk  fowls  may  fre- 
quently or  occasionally  be  met  with,  which  are  almost  identical  in  plumage 
with  the  wild  G.  baiikiva.''  But  does  this  indicate  anything  else  than  that 
this  type  of  coloration  has  persisted  in  certain  primitive  races,  like  the  Game, 
and  has  been  transplanted  from  them  to  the  new  races  ?  Darwin  crossed  a 
black  Spanish  cock  with  various  white  and  white- and-black  hens  of  pure 
breed.  The  offspring  of  this  cock  crossed  with  a  silver-spangled  Polish  hen 
and  with  a  white  Cochin  hen  showed  no  sign  of  reversion  to  the  red  color  of 
G.  ba?ikiva.  The  male  offspring  of  a  spangled  or  silver  Hamburgh  hen 
showed  white  in  the  hackles  and  a  reddish  yellow  on  the  saddle.  Darwin 
regarded  this  as  a  "  first  sympton  of  reversion  ;  "  but  in  the  first  of  these 
peculiarities  the  hybrid  resembles  G.  bankiva  less  than  the  Dark  Brahma. 
The  offspring  of  a  white  Game  hen  with  the  Spanish  cock  was  at  first  snow 
white,  but  eventually  produced  the  "pile"  coloration.  Darwin  regards 
this  as  a  partial  reversion  to  G.  bankiva  ;  but  it  is  equally  possible  that  the 
reversion  is  only  to  a  pile  coloration  that  is  latent  in  the  white  from  an  earlier 
cross  and  is  brought  out  when  the  white  is  crossed  with  a  dark  color.  But 
Darwin's  most  remarkable  hybrid  was  the  offspring  of  a  white  Silky  hen. 
Of  two  cockerels  one  was  black  (with  light  laced  hackles)  ;  the  other  resem- 
bled closely  a  Jungle  cock.     Darwin  admits  that  the  case  is  extraordinary, 


GENERAI,   TOPICS   IN    INHERITANCE.  91 

but  it  was  duplicated  by  Mr.  Tegetmeier.     This  experiment  certainly  should 
be  repeated,  and  I  have  arranged  to  repeat  it  next  season. 

One  of  the  best  cases  of  reversion  is  the  gray  coat  of  a  hybrid  between  a 
white  and  a  black  mouse.  We  now  know,  however,  that  even  a  "pure 
race ' '  of  white  mice  may  carry  gray  as  a  latent  characteristic  that  first  be- 
comes patent  on  crossing.  In  view  of  such  facts  cases  of  "  reversion  "  to  a 
remote  ancestor  must  be  critically  examined.  If  the  "  reversion  "  be  not  a 
neomorph,  it  must  have  been  handed  down  without  break  in  the  germ 
plasm  from  an  ancestor  possessing  the  characteristic. 

PURITY   OF   GAMETKS. 

The  dogma  of  purity  of  the  gametes,  the  second  corner-stone  of  Mendelism, 
asserts  that  while  the  unripe  germ  cells  of  a  hybrid  having  antagonistic  or 
alternative  characteristics  A  and  A'  contain  representatives  of  both  A  and 
A' ,  yet  the  ripe  germ  cells  of  such  a  hybrid  contain  representatives  of  either 
A  or  A' ,  and  not  of  both.  Thus  the  ripe  germ  cells  (gametes)  are  pure  in 
respect  to  a  given  characteristic.  They  gain  this  purity,  it  is  supposed,  dur- 
ing the  maturation  period,  the  period  when  the  reduction  division  of  the 
chromosomes  occurs,  and  when  in  each  cell  division  one-half  of  each  chro- 
mosome moves  bodily  to  one  daughter  cell  and  one  half  to  the  other.  The 
theory  assumes,  of  course,  that  characteristics  A  and  A' ,  being  derived  from 
different  parents,  inhere  in  different  chromo^:omes.  Let  us  assume  that  our 
hybrid  has  eight  chromosomes,  four  derived  from  each  parent,  thus  : 

.0  •      o 

o      • 

in  which  the  black  dots  represent  chromosomes  of  maternal  origin  ;  the 
circles  chromosomes  of  paternal  origin.  If  all  maternal  chromosomes  contain 
the  determinant  a  then  purit}^  of  the  gametes  demands  that  all  such  go  to 
one  gamete  and  all  of  the  chromosomes  of  paternal  origin  go  to  the  other, 
and  that  such  is  their  behavior  has  in  fact  been  assumed  by  Cannon  (1902). 
But  that  would  result  in  the  extracted  pure  individuals  of  the  second  hybrid 
generation  being  like  their  grandmother  or  their  grandfather  in  all  charac- 
teristics, which  is  not  the  case.  If  we  assume  that  some  only  of  the  maternal 
chromosomes,  such  as  are  represented  by  the  small  dots,  contain  the  deter- 
minant a,  then  these  may  be  a.ssociated  with  an}'  of  the  paternal  chromo- 
somes excepting  those  that  contain  the  determinant  a' .  Such  a  selection  of 
chromosomes  so  as  to  exclude  from  the  ripe  gamete  chromosomes  containing 
both  the  alternative  characteristics  is  quite  possible,  owing  to  the  fact  of 
synapsis,  in  which  the  homologous  chromosomes  from  the  two  parents  unite 
in  pairs,  as  shown  in  the  figure,  in  such  a  way  that  both  can  not  pass  to  the 
same  gamete. 

The  foregoing  hypothesis  of  Sutton  (1902,  1903)  and  Boveri  (1902)  would 
account  for  perfect  purity  of  gametes.     But  it  is  clear  that  gametes  are  not 


92  INHERITANCE    IN    POULTRY. 

wholly  pure,  since  the  characteristics  in  second  generation  hybrids  are  rarely 
exactly  like  those  of  their  grandparents  ;  consequently  various  additional 
hypotheses  have  been  offered  accounting  for  this  feature.  Hacker  (1904) 
points  out  that  chromosomes  do  not  pass  from  cell  to  cell  unchanged  except 
for  their  growth  and  division.  During  the  resting  stage  "of  the  nucleus  it 
disappears.  The  new  nucleus  which  arises  in  the  position  of  the  old  is  at 
first  small  ;  it  arises  inside  of  the  old  chromosome  as  a  spore  arises  in  the 
mother  cell ;  its  material  has  been  derived  from  a  part  only  of  that  of  the 
mother  chromosome  ;  the  remainder  goes  to  form  part  of  the  cytoplasm. 
Though  chromosomes  from  different  parents  tend  to  separate  to  distinct 
gametes,  still  all  gametes  are  infected  by  each  kind  of  characteristic." 
McClung  (1905,  p.  329)  assumes,  more  vaguely,  a  mutual  influence  of  synap- 
tically  paired  chromosomes  in  the  prophase  of  the  first  spermatocyte. 

A  different  suggestion  is  offered  by  Ziegler  (igos).  He  assumes  that  each 
chromosome  of  maternal  or  of  paternal  origin  carries  determinants  of  all 
characteristics.  After  maturation  all  gametes  contain  the  same  number  of 
chromosomes,  but  the  proportion  in  them  of  chromosomes  of  paternal  and 
of  maternal  origin  varies.  Gametes  rarely  contain  exclusively  maternal  or 
paternal  chromosomes,  but  whenever  the  proportion  from  one  parent  is  high 
the  gamete  acts  as  though  it  contains  exclusively  the  gametes  of  that  one 
ancestor.  If  two  gametes  that  are  prevailingly  paternal  unite  in  a  zygote 
the  resulting  hybrids  (of  the  second  generation)  show  all  the  grand-paternal 
characteristics.  The  difficulty  with  this  hypothesis  is  that,  like  Cannon's, 
it  does  not  account  (any  better  than  the  first  hypothesis)  for  the  diverse 
combinations  of  characteristics  shown  in  the  second  hybrid  generation. 

Still  another  suggestion  has  been  made  by  Morgan  (1905).  It  is  that  the 
gametes  are  not  pure,  but  contain  determinants  of  both  allelomorphs  a  and 
a',  and  that  one  of  these  dominates  in  half  of  the  gametes  and  the  other  in 
the  remaining  half.  The  advantage  of  this  hypothesis  is  that  it  accounts 
for  latent  dominant  characters  in  recessive  individuals.  This  hypothesis 
assumes  that  the  gametes  of  hybrids  are  alwaj^s  impure,  and  that  this  im- 
purity can  not  be  got  rid  of.  This  seems  to  me  to  be  contrary  to  experience. 
Moreover,  except  for  the  explanation  that  it  offers  of  latency — which  has 
been  accounted  for  on  other  grounds  by  Cuenot — it  offers  no  practical  advan- 
tage over  the  theory  of  pure  gametes. 

From  the  foregoing  diversity  of  hypotheses  it  is  evndent  that  we  lack  a  fully 
satisfactory  cytological  explanation  of  the  facts  other  than  that  of  purity — 
the  fact  of  imperfect  dominance  and  the  fact  of  particulate  inheritance  com- 
bined with  purity  in  the  second  hybrid  generation.  Perhaps  it  will  suffice 
to  suppose  a  restricted  purity  of  gametes  such  that  the  determinant  of  a 
characteristic  may  become  infected  to  a  slight  degree  by  the  presence  of  its 
allelomorph. 


GENERAL   TOPICS   IN    INHERITANCE.  93 

COMPARISON   OF   RECIPROCAL   CROSSES. 

There  is  a  notion  among  breeders  of  poultry  that  the  father  and  the  mother 
contribute  different  qualities  to  the  offspring  ;  and  if  the  cytoplasm  carries 
any  hereditary  tendencies  this  result  is  to  be  expected,  for  the  female  trans- 
mits more  cytoplasm  than  the  male.  Certainly  the  hybrid  between  a  large 
hen  and  a  bantam  cock  starts  life  on  a  very  different  plane  of  size  from  the 
hybrid  between  a  bantam  hen  and  a  large  cock.  A  writer  in  Wright's 
Poultry  Book  (1902)  says  in  respect  to  breeding  Houdans  that  the  male  bird 
is  more  responsible  for  the  outside  qualities — color,  size  of  crest,  beard,  tail 
carriage,  color  of  legs,  and  so  on.  The  hen  determines  laying  qualities  and 
general  size. 

I  have  made  only  one  extensive  experiment  on  this  matter.  I  crossed  a 
single-comb  White  lyCghorn  bantam  and  a  Dark  Brahma  both  ways.  The 
offspring  of  the  Dark  Brahma  hen  (weight.  1,300  grams)  are  a  little  heavier 
than  those  of  the  White  I^eghorn  bantam  hen  (weight,  700  grams).  Two 
males  descended  from  the  one  and  the  other  mother,  respectively,  weighed 
at  3^  months  720  and  550  grams.  The  average  of  three  pullets  from  the 
Dark  Brahma  at  3  months  22  days  is  655  grams  ;  of  three  pullets  from  the 
White  lyCghorn  at  3  months  23  days  is  626  grams.  The  proportional  differ- 
ence in  the  weight  of  the  young  of  about  3  to  4  months  is  less  than  that  of 
their  parents,  but  is  in  the  same  sense. 

The  booting  of  the  offspring  of  the  White  I,eghorn  hen  is  much  reduced 
as  compared  with  the  booting  of  the  offspring  of  the  Dark  Brahma  hen,  the 
father  in  the  first  cross  not  differing  from  the  mother  in  the  second  cross 
in  its  heavy  booting.  In  plumage  color  the  19  offspring  of  the  White  Leg- 
horn  female  were  all  white  except  four.  Of  the  19  offspring  of  the  Dark 
Brahma  female,  only  six  were  white,  the  others  resembling  the  Dark  Brahma. 
Thus  we  see  that  in  these  three  characters  of  weight,  booting,  and  plumage 
color  the  offspring  tended  to  ' '  take  after  ' '  the  mother. 

INHERITANCE  OF  SEXUALITY  DIMORPHIC  CHA  RACTERISTICS  AND  SEXUAL 

DIMORPHISM  IN  THE  HYBRIDS. 

Most  species  of  vertebrates  exhibit  certain  characteristics  peculiar  to  one  or 
the  other  sex,  and  it  is  well  known  that,  for  example,  a  female  peculiarity 
can  be  transmitted  through  a  son  to  a  granddaughter.  Thus  the  good 
milking  quality  of  a  cow  is  transmitted  through  her  son  to  his  daughters. 
Whenever  femaleness  crops  out  in  the  history  of  the  germ  plasm  the  good 
milking  quality,  or  whatever  other  quality  it  may  be,  also  appears.  The 
inheritance  of  dimorphic  characters  is  most  strikingly  seen  in  hybridization. 
Thus  I  crossed  a  male  Tosa  fowl  (which  has  self-colored  feathers  1  with  a 
white  Cochin.-'^  The  male  hybrids  are  barred  with  white,  but  the  female 
hybrids  closely  resemble  in  color  the   female  Tosa  fowl  in  having  white 


*  See  Series  IX. 


94  INHERITANCE    IN   POULTRY. 

shafting  on  the  contour  feathers,  although  the  white  shafting  is  much 
broadened.  When  the  barred  male  and  broad-shafted  females  of  this  first 
hvbrid  generation  were  crossed  the  pure  plumage  of  the  Tosa  fowl  tends  to 
reappear.  The  males  have  contour  feathers  without  white  and  with  much 
red  ;  the  females  have  the  shafted  feather  without  any  red.  With  maleness 
or  femaleness  go  the  proper  secondar}'  attributes. 

What  is  true  of  the  Tosa  fowl  is  true  generally,  and  there  is  much  oppor- 
tunity to  test  this  matter  in  poultry,  for  sexual  dimorphism  is  widespread. 
In  all  "dark"  or  "partridge,"  silvered,  and  golden  races  as  found  iu 
Brahmas,  Cochins,  Wyandottes,  Dorkings,  Hamburghs,  Games,  and  Oriental 
fowl,  the  plumage  of  the  two  sexes  is  conspicuously  different  ;  and  to  pro- 
duce sexual  dimorphism  in  a  race  that  is  without  it  the  use  of  one  male 
bird  of  a  dimorphic  race  may  suffice.  Again,  in  the  male,  comb  and  wattles 
are  generally  larger  than  in  the  female.  The  rose  comb  of  the  male  becomes 
often  a  modified  pea  comb  in  the  female.  The  simple  comb  of  the  Minorca, 
Spanish,  and  Dorking  fowl  is  erect  in  the  male,  drooping  to  one  side  (equally 
to  the  right  and  left  side)  in  the  female.  The  form  of  the  hackle  and  saddle 
feathers  constitutes  one  of  the  most  constant  differences  between  the  two 
sexes.  These  are  long,  narrow,  and  pointed  in  the  male  ;  short,  broad,  and 
rounded  in  the  female.  The  tail  feathers  differ  similarly.  The  sickle  feathers 
and  those  of  the  middle  row  especially  continue  to  grow  in  the  male  long  after 
their  growth  has  ceased  in  the  female.  Similarly  the  crest  feathers  of  Polish 
and  Houdans  grow  longer  in  the  male  than  in  the  female,  but  on  account  of 
theirgreater  breadth  in  the  female  her  crest  appears  larger  and  fuller.  Lastly, 
the  greater  development  of  the  spurs  in  the  male  over  six  to  eight  months 
old  is  a  well-marked  dimorphic  character.  Of  these  characters  I  have  paid 
most  attention  to  plumage  and  skin  color,  and  will  take  up  in  review  the 
results  gained  in  crossing  dimorphic  species. 

Black  Minorca  and  Dark  Brahma. — The  male  Dark  Brahma  has  white- 
laced  hackles  and  black,  white,  and  red  wing  bars.  In  the  female  the  lacing 
on  the  hackles  is  less  conspicuous,  and  there  are  no  wing  bars  or  bows. 
Red  is  wholly  absent.-  All  hybrids  are  prevailingly  black.  All  males,  how- 
ever, show  a  more  or  less  prominent  wing-bar  formed  of  black,  straw,  and 
red  colored  feathers.  No  females  show  any  trace  of  a  wing  bar  unless  it  be  a 
slight  iridescence  in  the  wing  coverts. 

White  Leghorn  and  Dark  Brahma. — The  male  hybrids  are  typically  white, 
with  some  red  on  wing  coverts.  Apart  from  some  black  individuals,  the 
female  hybrids  are  either  white,  with  some  buff  on  wing,  or  else  they  resem- 
ble the  female  Dark  Brahma,  having  the  penciling  modified  into  mossiness. 
There  is  no  well-defined  wing-bar,  but  the  middle  wing  is  suffused  with  red. 

White  Leghorn  a?id  Hotidayi. — Neither  of  these  races  exhibits  a  marked 
dimorphism  in  plumage  color.  Nevertheless,  the  coloration  of  the  hybrids 
is  dissimilar  in  the  two  sexes,  the  males  being  of  a  much  purer  white  than 


GENERAL  TOPICS   IN   INHERITANCE.  95 

the  females  (p.  21),  and  this  is  true  not  only  in  the  first  generation,  but  also 
in  the  extracted  whites  of  a  later  generation. 

White  LegJiorn  and  Rose-comb  Black  Minorca. — In  the  first  generation  the 
male  hybrids  were  almost  without  exception  pure  white  ;  the  female  hybrids 
invariably  show  some  black-speckled  feathers. 

Tosa  fozvl  and  White  Cochin  Bantain. — In  the  first  hybrid  generation,  as 
stated,  the  males  had  all  feathers  of  male  Tosa  coloration,  but  barred  with 
white.  The  females  had  the  Tosa  hen  coloration,  but  with  shafting  broad- 
ened. Here  each  sex  inherits  the  corresponding  characteristic  plumage  of 
the  Tosa  fowl  modified  by  the  white  of  the  Cochin,  but  in  different  fashion 
for  each  sex.  Barring  or  cuckoo  marking  seems,  indeed,  a  prevailingly  male 
characteristic.  Hurst  (1905,  p.  133),  in  crosses  of  White  Leghorn  and 
Houdan,  got,  in  addition  to  white  hybrids,  11  dark  birds  ;  of  these  the  6 
pullets  were  black  ;  the  5  cockerels  were  barred. 

In  the  F,  generation  I  obtained  extracted  pure  (?)  male  and  female  Tosa- 
fowl  plumage  as  well  as  pure  whites  (p.  49). 

Dark  Brahma  {female)  and  Tosa  Jowl  {tnale).  —  Here  both  races  are 
dimorphic.  The  female  hybrids  closely  resembled  in  coloration  the  female 
Tosa  fowl,  except  that  the  contour  feathers  were  penciled  as  in  the  Brahma. 
The  male  hybrids  closely  resembled  in  coloration  the  male  Dark  Brahma, 
except  that  much  more  red  and  less  white  appeared  on  the  wing  bars  and 
wing  bows.  Both  sexes  inherit  some  qualities  from  the  corresponding  sex 
of  each  of  the  parent  species.  Again,  the  males  have  a  yellow  foot  like  their 
mother,  whereas  the  females  have  a  willow  foot  like  their  father.  The  hybrids 
of  either  sex  inherit  foot-color  from  the  opposite  sex  of  their  parents  (p.  54). 

TRANSFER  OFSEXUAIXY  DIMORPHIC  CHAR ACTKRISTICS  FROM  ONE  SEX  TO  THE  OTHER. 

Secondary  sexual  characters,  such  as  have  been  referred  to  in  the  last  sec- 
tion, seem  indissolubly  associated  with  their  corresponding  sex.  The  reason 
for  such  an  association  is  obscure,  but  it  is  known  that  it  is  not  due  to  the 
absence  in  the  protoplasm  of  the  characteristics  of  the  opposite  sex,  for  these 
may  develop  in  the  individual  when  the  germ  glands  are  removed.  The  germ 
glands,  then,  control  the  latency  of  the  one  set  of  characters  and  the  patency 
of  the  other  set.  In  poultry  the  removal  of  the  sex  glands  from  a  young 
cock,  in  the  process  of  caponizing,  results  in  loss  of  the  crowing  instinct  and 
failure  of  comb,  wattles,  spurs,  hackle,  saddle,  and  sickles  to  acquire  the 
size  characteristic  of  a  cock.  If  in  the  fowl  the  germ  glands  fail  to  develop, 
the  secondary  sex  characters  are  ambiguous. 

Despite  this  apparently  physiological  dependence  of  secondary  characters 
in  the  germ  gland,  it  seems  improbable  that  the  association  is  a  necessary 
one.  Almost  all  characters  can  be  dissociated  ;  wh}''  not  also  sex  and  second- 
ary characters  ?  There  is  reason  to  think  much  can  be  done  in  this  way, 
because  something  has  alreadj^  been  accomplished.     For  example,  the  cereb- 


96  INHKRITANCK    IN    POULTRY. 

ral  hernia  which  now  is  found  equally  in  both  sexes  of  the  Polish  fowl  was 
formerly  a  female  secondary  sexual  characteristic.  Bechstein  (1793)  states 
that  he  never  observed  the  cranial  dome  in  male  Polish  fowl.  Blumenbach 
(1813),  who  made  numerous  dissections  of  the  cranium  of  this  fowl,  states 
"of  this  deformit}'  very  slight  traces  indeed  are  found  in  the  cocks,  and 
these  but  seldom. ' '  *  Consequently  it  must  be  concluded  that  the  female 
secondary  characteristic  of  cerebral  hernia  has  been  gradually  transferred 
to  the  male  sex  also.  A  case  of  which  the  history  is  known  even  more  defi- 
nitely is  that  of  the  vSebright  Bantam.  This  bird  is  characterized  by  the 
fact  that  in  the  male  the  hackle,  saddle,  and  sickle  feathers  are  of  the  same 
form  as  in  the  female  ;  consequently  the  tail  is  short  and  truncate  as  in  a 
hen.  Here,  apparently,  female  characteristics  have  become  attached  to  a 
male.  Fortunately  we  have  the  history  of  the  race  from  the  mouth  of  the 
son  of  the  maker,  Sir  Thomas  Sebright.  Dr.  Horner,  who  obtained  the  state- 
ment from  Sebright,  published  it  in  Tegetmeier's  Poultry  Book  (1868,  pp. 
241,  242). 

It  was  about  the  year  1800  that  the  late  Sir  John  Sebright  began  to  fashion  the  Sebright 
Bantam.  The  first  cross  was  between  a  common  I^antamf  and  the  Polish  fowl.|  The 
chickens  resulting  from  this  alliance  were  bred  in-and-in  until  the  required  markings 
and  size  were  secured.  Sir  John  then  accidentally  found  a  hen-tailed  Bantam  cock  in 
the  country  where  he  was  traveling.  This  short-tailed  bird  he  in-bred  with  his  newly 
manufactured  Bantams,  thereby  giving  their  progeny  the  present  form  of  the  square  tail. 

The  essential  characteristic  of  the  race  was  thus  gained  from  a  mutative 
modification  of  a  polymorphic  characteristic. § 

In  my  own  experiments  I  have  hardl}''  proceeded  far  enough  to  get  results  ; 
yet  already  evidence  of  transference  of  color  characteristics  from  one  sex 
to  the  other  is  appearing.  Thus  in  the  .second  hj^brid  generation  of  the 
Cochin  X  Tosa  cross  at  least  one  bird  (No.  659  9  )  kas  hackles  of  a  plain 
buff  color  like  those  of  the  male  Tosa  fowl,  and  entirely  unlike  the  hackles 
of  the  female  Tosa  fowl  or  the  female  of  the  dark  variety  of  the  Cochin. 
Again,  the  female  hybrids  between  the  Dark  Brahma  hen  and  White  Leghorn 
cock  have  much  red  on  the  wing  coverts.  This  is  foreign  to  the  Dark  Brahma 
hen,  and  must,  so  far  as  I  can  see,  have  been  derived  from  the  red  on  the 
wings  of  the  male  Tosa  fowl.  Finally,  two  male  hybrids  between  the  Tosa 
fowl  and  Dark  Brahma  show  the  feminine  shafting.  Experiments  in  con- 
tinuance of  this  investigation  are,  naturally,  in  progress. 

*  Translation  quoted  by  Tegetmeier,  1867,  p.  173. 

t  Doubtless  Game  Bantam  is  here  meant. 

t  The  Golden  Spangled  Polish  are  undoubtedly  referred  to,  whence  the  spangling  of  the 
feather  was  obtained.     The  combination  gave  the  small  size  and  gold-spangled  plumage. 

§  As  might  be  anticipated  from  the  notoriously  sterile  quality  of  hen-feathered  cocks, 
Sebright  Bantams  are  inclined  to  be  sterile,  and  one  is  advised  not  to  try  to  breed  from 
the  best  show  stock.  7.  e.,  cocks  with  the  shortest  tails  (Wright,  1902,  p.  598). 


GENERAL  TOPICS   IN    INHERITANCE.  97 

SEX  IN  HYBRIDS. 

There  is  a  widely  held  and  frequently  expressed  opinion  that  hybrids  show 
an  excessive  proportion  of  males.  Bate.sou  and  Saunders  (1902,  p.  139) 
probably  have  this  in  mind  in  their  statement — "  the  statistical  distribution 
of  sex  araonof  first  crosses  shows  great  departure  from  the  normal  propor- 
tions." I  have  therefore  been  interested  to  tabulate  the  sex  proportions 
in  my  hybrids.  Without  giving  the  full  table,  I  may  state  that  the  totals 
are  :  Males,  204  ;  females,  173  ;  sex  undetermined,  573.  There  is  here  an 
excess  of  males  ;  but  in  view  of  the  large  early  death  rate,  this  may  well  be 
due  to  a  difference  in  the  death  rate  of  the  two  sexes.  Taking  the  different 
series  of  hybrids  separately,  most  of  them  gave  an  approximation  to  equality 
of  the  sexes.  One  of  the  most  striking  departures  is  the  series  of  Dark 
Brahma  (121  $)  X  Tosa  (8a  ^)  hybrids.  Of  22  individuals  that  developed 
to  18  days  in  the  incubator,  all  but  one  grew  to  maturity.  Of  these  21,  16 
are  males  and  5  females.  The  first  egg  laid  by  the  Dark  Brahma  after  she 
was  put  with  the  Tosa  fowl  developed  into  a  female  ;  the  next  nine  that 
hatched  were  males  ;  also  her  last  six  young  were  males.  The  exceptions 
to  the  law  of  equality  of  sexes  in  hybrid  offspring  are  thus  individual  and 
not  of  general  significance. 

CORRELATION  OF   CHARACTERISTICS. 

Every  taxonomic  description  testifies  to  the  fact  that  a  certain  set  of 
characteristics  is  usuall)'-  found  associated  in  each  species  or  variety.  The 
prevailing  theory  has  been  that  this  association  is  a  necessary  one,  maintained 
because  all  the  characters  are  necessary  to  the  success  of  the  species  in  its 
relations  to  external  environment,  or  else  that  they  were  physiologically  inter- 
dependent. Modern  work  in  hybridizing  is  establishing  the  fact  that  few  of 
the  specific  characteristics  are  interdependent.  Their  association  is,  so  far 
as  interaction  goes,  mostly  accidental.  Thus  in  my  experiments  with  poultry 
I  have  merely  reached  the  same  conclusions  as  have  been  gained  by  Johannsen 
(1899,  p.  185),  de  Vries  (1903,  p.  494),  and  indeed  all  recent  workers.  I 
find,  namely,  that  of  the  scores  of  evident  external  characteristics  of  poultry 
that  are  inherited  in  alternative  fashion  scarcely  two  can  be  found  that  are 
always  associated.  The  most  striking  exception  is  the  association  of  high 
nostril  and  absence  of  single  comb. 

What,  then,  is  the  meaning  of  correlation  in  nature?  Clearly  it  is  only 
rarely  due  to  physiological  interdependence.  It  may  often  be  due  to  an 
unrelated  association  of  characters  independently  advantageous  to  the  organ- 
ism. It  is  doubtless  due  to  an  accidental  association  of  characters  brought 
into  the  race  by  successive  mutations  or  by  hybridizations  and  never  disturbed, 
because  not  prejudicial  to  the  well-being  of  the  species. 


98  INHERITANCE   IN   POULTRY. 

THE  MrTATION  THEORY  IN  ITS  RELATION  TO  THE  ORIGIN  OF  DOMESTICATED  ANIMALS. 

While  the  mutation  theorj'  of  de  Vries  has  received  widespread  adherence 
among  botanists,  many  students  of  animals,  and  especially  of  domesticated 
races,  have  appeared  as  its  opponents.  Foremost  among  these  are  Professors 
Keller,  of  Zurich  (1905),  and  Plate  (1905),  of  Berlin.  I  think  that  the  essence 
of  the  mutation  theory  is  too  little  apprehended.  It  rests  on  the  funda- 
mental theory  of  heritable  unit  characters  and  assumes  their  very  limited 
mutability.  It  recognizes  the  important  results  wrought  by  artificial  selec- 
tion, but  considers  them  as  arising  from  two  processes — first,  the  selection  of 
minute  favorable  variations  of  the  fluctuating  sort,  and,  secondlj^  the  preser- 
vation of  new  unit  characters  suddenly  appearing.  Such  unit  characters  can 
usually  be  not  only  maintained  but  much  improved  by  subsequent  selective 
breeding. 

Now,  it  is  true  that  breeders  nowadays  do  not  regularly  wait  for  favorable 
qualities  to  crop  out.  The  process  is  too  slow,  uncertain,  and  expensive.  If 
one  had  scores  of  thousands  of  individuals,  desired  mutations  would  come 
more  frequently  ;  but  even  then  they  would  rarely  be  of  a  desirable  sort. 
Every  breeder  can,  on  the  other  hand,  improve  any  characteristic  by  selec- 
tion, and  that  is  for  the  most  part  the  only  method  of  improving  a  quality 
that  is  open  to  him.  Of  course  he  can  make  new  combinations  of  qualities 
by  crossing,  but  this  does  not,  typically,  result  in  new  qualities. 

The  question  of  the  permanence  of  the  improvement  wrought  by  selection 
of  minute  variations  is  the  first  point  of  difference  between  de  Vries  and 
Keller.  De  Vries  asserts  that  such  improvement  persists  only  so  long  as 
selection  is  maintained.  Keller  adduces  some  interesting  cases  on  the  other 
side,  and  the  cogency  of  some  of  his  evidence  must  be  admitted.  He  traces 
the  gradual  evolution  in  Egypt  of  long  lop-eared  hounds  from  straight-eared 
ones.  Ear  length  in  rabbits,  as  Castle  (1905,  pp.  125-126)  has  shown,  is  not  a 
unit  character  ;  at  least,  it  blends  in  hybridization  and  con.sequently  exhibits 
any  desired  intermediate  condition.  The  same  is  probably  due  for  dogs  ; 
consequently  this  character  may  well  have  arisen  by  summation  of  minute 
variations.  Yet  Keller  goes  on  to  show  the  long-eared  condition  has  per- 
sisted in  central  Africa,  where  selective  breeding  no  longer  occurs.  Hence 
one  characteristic  originated  by  selection  of  fluctuations  has  not  retrogressed 
on  removal  of  selection. 

The  preceding  method  of  proof  is  not,  however,  of  general  validity. 
Evidence  that  a  characteristic  arisen  in  domestication  does  not  disappear 
when  the  race  becomes  feral  again  is  not  evidence  against  the  permanence 
of  fluctuations  unless  it  is  also  proven  that  the  characteristic  arose  by  selec- 
tion of  fluctuations.  This  is  usually  not  the  case.  The  instance  of  long 
ears  would  seem  to  be  peculiar.  Some  of  the  other  examples  offered  by 
Keller  of  persistence  of  characteristics  despite  discontinuance  of  selection 
avail  little,  since  the  precise  origin  of  the  unit  characters  concerned  is  un- 


GENERAL  TOPICS   IN   INHERITANCE.  99 

known.  If,  unconsciously  or  not,  a  unit  character  arising  as  a  sport  has 
been  preserved  under  domestication,  it  will  persist  even  though  the  race 
bearing  it  become  feral. 

Positive  support  for  the  mutation  theory  is  gained  from  a  consideration  of 
the  characteristics  of  poultry.  Our  study  has  shown  them  to  be,  for  the 
most  part,  of  the  order  of  integral  unit  characters.  As  such  they  could 
hardly  have  been  "  gradually  built  up."  Being  indivisible  they  must  have 
appeared  at  once,  roughly  in  their  present  form.  The  very  existence  of  unit 
characters  is  proof  of  the  mutation  theory. 

That  many  characteristics  of  organisms  have  not  been  built  up,  but  have 
suddenly  appeared  complete,  may  be  inferred  from  peculiarities  of  the  char- 
acters other  than  their  integral  nature.  For,  first,  not  all  kinds  of  charac- 
teristics have  been  evolved  in  domestic  poultry,  but  for  the  most  part  only 
such  as  occur  elsewhere  among  wild  races.  Thus,  for  example,  booted  feet, 
as  found  in  the  grouse  ;  crest  on  head,  as  seen  in  the  umbrella  bird  {Ccphahp- 
terus),  and  long  tail,  as  seen  also  in  the  widow  bird  {Chera).  Secondly, 
many  of  the  characteristics  of  domestic  poultry  are  of  the  order  of  mutations 
in  so  far  as  they  are  almost  pathological,  e.  {r.,  taiUessness,  rose  comb,  silky 
and  frizzled  feathers,  cerebral  hernia,  polydactyl  feet,  albinism.  These  char- 
acters, cropping  out  in  the  sporting  organism  and  not  being  prejudicial  to 
its  well-being,  have  been  preserved  by  the  fancier  ;  they  doubtless  arose  sud- 
denly, as  we  find  arising  suddenly  to-day  other  characters,  which  we  discard 
because  incompatible  with  a  healthy  stock — such  as  featherlessness,  cross-bill, 
and  imperfect  development  of  toes.  If  these  characteristics  appeared  sud- 
denly and  not  by  being  "built  up,"  as  we  know  is  the  case,  then  so,  doubt- 
less, have  others.  The  evidence  that  many,  if  not  most,  characteristics  of 
poultry  have  arisen  suddenly,  without  having  been  sought  and  laboriously 
built  up  by  man,  is  convincing,  and  there  can  hardly  be  any  escape  from  the 
conclusion  that  here  evolution  has  bee.i  largely,  though  not  exclusively,  by 
mutation. 


lOO  INHKRITANCE    IN    POULTRY. 

E.  SUMMARY  OF  CONCLUSIONS. 

(i)  Poultry  exhibit  nnnieroiis  unit  characteristics  which  do  not  blend  in 
hybridization,  but  are  inherited  in  alternative  fashion.  The  unit  characters 
are  not  immutable  things  in  hybrids,  but  subject  to  modification — perhaps 
permanent — by  interaction  of  the  alternative  characters. 

(2)  Although  the  great  majority  of  characteristics  of  poultry  are  inherited 
alternatively,  yet  a  few  cases  of  color  characters  show  a  particulate  inher- 
itance. The  comparative  rarity  of  blending  of  characters  makes  it  easier  to 
see  how  new  characters  will  not  be  ' '  swamped  by  intercrossing  with  the 
parent  form  "  (page  82). 

(3)  Specific  and  varietal  characteristics  in  de  Vries's  sense  are  not  inherited 
in  a  markedly  different  fashion,  although  in  two  cases  progressive  variants 
do  not  Mendelize  typically. 

(4)  The  patent  characteristic  is  usualh^  dominant  over  its  latent  allelo- 
morph. 

(5)  Old  and  new  characteristics  are  equall}^  dominant. 

(6)  Dominance  and  recessiveness  of  characteristics  are  not  always  accom- 
paniments of  their  segregation  in  the  germ  cells ;  both,  moreover,  are  fre- 
quently incomplete. 

(7)  Dominance  is  usually ,  but  not  always,  independent  of  the  races  crossed. 

(8)  Prepotency  is  as  truly  important  in  inheritance  as  dominance. 

(9)  Many  first  hybrids  exhibit  special  forms,  due  to  the  interaction  of  the 
two  allelomorphs.     These  may  become  fixed  as  new  characteristics. 

(10)  Reversion  is  being  explained  bj^  the  persistence  in  a  "latent" 
condition  of  the  latent  character. 

(11)  An  adequate  theory  of  gametic  purity  has  not  only  to  explain  the 
simple  Mendelian  formula,  but  also  the  facts  of  imperfect  dominance,  im- 
purity of  extracted  forms,  latency  and  atavism,  and  occasional  particulate 
inheritance. 

(12)  Reciprocal  crosses  exhibit  differences  due  to  the  fact  that  the  father 
and  the  mother  transmit  different  kinds  of  characteristics. 

(13)  When  the  parent  races  are  dimorphic  each  .sex  in  the  hybrids  exhibits 
the  respective  sex  characteristic  of  both  of  the  species.  In  many  cases  a 
new  form  of  sexual  dimorphism  appears  in  the  hybrids. 

(14)  Certain  characteristics  of  one  sex  may  become  transferred  to  the 
other  by  hybridization,  owing  to  lack  of  complete  correlation  between  primary 
and  secondary  sex  characters. 

(15)  The  proportion  of  the  two  sexes  in  hybrids  is  normal. 

(16)  With  few  exceptions,  correlated  characteristics  easily  separate  as  a 
result  of  hybridization  so  that  any  conceivable  combination  may  be  effected. 

Carnegie  Institution, 

Station  for  Experimental  Evolution, 

Cold  Spring  Harbor,  February  12,  igo6. 


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1904.  The  evolution  theory.     Trans,  by  J.  A.  Thomson  and  M.  R.  Thomson.     2  vols. 
Loudon  :  Arnold,     xvi  -f  416  -f-  405  pp. 
Woods,  F.  A. 

1902-03.   Mental  and  moral  heredity  in  royalty.     Popular  Science  Monthly.     .\ug. 
1902-April,  1903. 
Wright,  L. 

1902.  The  new  book  of  poultry.     London,  etc.  :  Cassell  &  Co.     viii  ^-  600  pp. 

Wyckofe,  E.  G. 

1904.  The  Leghorns.     In  Weir-Johnson-Brown  Poultry  Book.     1904-05  {q.  v.). 

ZlEGEER,  H.  E. 

1905.  Die  Vererbungslehre  in  der  Biologic.     Jena  :  Fischer.     74  pp.     2  Taf. 


I04  INHERITANCE   IN   POULTRY. 


EXPLANATION  OF  PLATES. 


PI.ATE  I. 


Pig.  I. — White  Crested  Black  Polish,  9  5-  One  of  the  females  crossed  with  the  Single- 
combed  Black  Minorca  ((/.  fig.  3)  to  produce  the  female  hybrid  shown  in 
fig.  5.     (H.A.  H.) 

Fig.  2. — White  Crested  Black  Polish,  r^  30.  To  show  the  male  type  of  the  Polish  race, 
which,  when  crossed  with  the  Minorca  (fig.  4),  produces  male  hybrids  like 
fig.  6.     (H.  A.  H.) 

Fig.  3. — Single  Comb  Black  Minorca,  9  13-  The  mother  of  the  hybrids,  Minorca  X  Polish, 
represented  by  fig.  5. 

Fig.  4. — Single  Comb  Black  Minorca,  cj'  12.  The  father  of  various  Polish  X  Minorca 
crosses,  of  which  a  male  is  represented  in  fig.  6. 

Fig.  5. — First  Hybrid  between  Polish  and  Minorca,  pullet.  Compare  the  females  of  the 
parental  races,  figs,  i  and  3. 

Fig.  6. — First  Hybrid  between  Polish  and  Minorca,  cockerel.  Compare  the  males  of  the 
parental  races,  figs.  2  and  4. 

The  fig^ures  marked  H.  A.  H.  are  from  photographs  made  by  Mr.  H.  A.  Hackett. 


PLATE  I. 


I06  INHERITANCE   IN   POULTRY. 


Pirate  II. 

Fig.  7. — The  head  of  a  Polish  fowl,  (^  3,  with  skin  on  left  half  of  head  dissected  away. 
Shows  cerebral  heruia,  and  the  relation  to  it  of  the  thick  skin  and  crest 
feathers  lying  above.  Note  also  the  cultninal  fold,  high  nostril,  and  rudi- 
mentary comb.  The  latter  lies  at  the  base  of  the  comb  and  shows  as  a 
mottled  area  against  the  deep  black  of  the  anterior  crest  feathers. 
(H.  A.  H.) 

Fig.  8. — Head  of  a  hybrid,  (^  50,  between  Minorca  9  13  (iig.  3)  and  Polish  ^f  3  (fig.  7). 
Shows  the  Y-shaped  comb  Ijing  in  front  of  the  crest.  The  comb  is  double 
behind,  single  in  front. 

Fig.  9. — Head  of  a  Minorca  X  Polish  hybrid  of  the  second  generation.  The  son  of  such  a 
pair  as  are  represented  in  figs.  5  and  6.  Note  the  reappearance  of  a  large 
crest,  high  nostril,  and  rudimentary  comb.     (H.  A.  H.) 

Fig.  10. — Side  of  cranium  of  Polish  fowl.     Shows  bony  dome  covering  cerebral  hernia. 


PLATE     II 


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I08  INHERITANCE    IN    POULTRY. 


Plate  ill. 

Fig.  ir. — Head  of  hybrid  of  the  second  generation,  Minorca  X  Polish,  371  (j" — the  son 
of  such  a  pair  as  are  represented  in  figs.  5  and  6.  Note  the  absence  (imper- 
fect) of  crest,  the  high  nostril,  and  the  rudimentary  comb.     (H.  A.  H.) 

Fig.  12. — Head  of  Houdan  {(^  9).      Shows  crest,  high  nostril,  and  rudimentary  comb. 

Fig.  13. — Foot  of  Houdan  {(^  9).  Shows  the  two  toes  (in  place  of  one)  situated  imme- 
diately below  the  spur. 

Fig.  14. — Head  of  second  generation  White  Leghorn  y  Houdan  hybrid,  its  father  being 
like  fig.  17.  Shows  the  occurrence  of  both  cerebral  hernia  and  single  comb 
on  the  same  individual,     (H.  A.  H.) 


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no  INHERITANCE    IN   POULTRY, 


PI.ATE  IV. 

Fig.  15. — Single  Comb  White  Leghorn  (cf  74).     Note  high  single  comb,  plain  head,  clean 
feet  with  four  toes,  and  white  plumage.     (H.  A.  H.) 

Fig.  16. — Houdan  (  9  8).     Note  crest,  high  nostril,  rudimentary  comb,  mottled  plumage, 
and  mufT  and  beard. 

Fig.  17. — First  hybrid  {^^f  87)  between  White  Leghorn  and  Houdan.     Note  crest,  Y  comb, 
white  plumage,  muff,  and  double  toe  behind  on  left  foot. 


PLATE  IV. 


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112  INHERITANCE   IN   POULTRY, 


Plate  V. 

Fig.  i8. — Dark  Brahma  hen  (121),  Note  uniformity  of  plumage  coloration,  except  that 
hackles  are  laced ^nih.  wbit?,  and'^\ing  coverts,  back,  and  breast  are  penciled. 
Comb  of  pea  type.     Feet  booted.     Vulture  hock.     (H.  A.  H. ) 

Fig.  19. — Dark  Brahma  cock  (122).  Isote  laced  hackles  and  saddles,  prominent  white 
wing  bow,  pea  comb,  and  booted  feet. 


PLATE  V. 


114  INHERITANCE    IN    POULTRY. 


Plate  VI. 

Fig.  20. — First  generation  hybrid,  (^  607,  between  Black  Minorca  (Sg.  6)  and  Dark 
Brahma  (fig.  19).  Note  prevailingly  black  plumage,  with  trace  of  white 
wing  bow,  irregular  pea  comb,  slightly  booted  feet,  and  absence  of  vulture 
hock  and  of  lacing  on  hackles.     (H.  A.  H.) 

Fig.  21. — First  generation  hybrid,  ^f'  603,  between  Black  Minorca  and  Dark  Brahma. 
Brother  to  fig.  20.  Note  almost  complete  absence  of  white  wing  bow,  but 
presence  of  white  lacing  on  hackles.  Note  also  high,  though  pea,  comb,  and 
long  tail.     Form  of  trunk  like  Dark  Brahma,  neck  like  Minorca,     (H.  A.  H.) 


PLATE    VI. 


Il6  INHERITANCE   IN   POUI^TRY. 


Pl,ATE  VII, 

Fig.  22. — First  generation  hybritl,  Q  387,  between  White  Leghorn  Bantam  (resembling 
fig.  15)  and  Dark  Brahma  (fig.  18).     Note  the  new  type  of  plumage  colora- 
tion.    Hackles  broadly  laced  as  in  male,  rest  of  plumage  mottled,  with  much 
red.     Booting  rudimentary.     (H.  A.  H. ) 

Fig.  23. — First  generation  hybrid,  9  395,  between   White  Leghorn  and  Dark  Brahma. 
Shows  reappearance  of  the  Dark  Brahma  9  tj'pe  of  coloration.     (H.  A.  H.) 


PLATE    VII 


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IlS  INHERITANCE    IN   POULTRY. 


PtATE  VIII. 

Fig.  24. — First  generation  hybrid,  cf  270,  between  White  Leghorn  and  Dark  Brahma. 
Shows  the  pure  white  t3'pe,  /.  ^.,  dominance  of  White  Leghorn  coloration. 
Note  slight  booting,  absence  of  vulture  hock  and  the  erect,  Leghorn  tail. 
(H.  A.  H.) 

Fig.  25. — First  generation  hybrid,  rf' 409 A,  between  White  Leghorn  and  Dark  Brahma. 
Shows  the  type  with  red  on  the  wing  coverts.     (H.  A.  H.) 


PLATE    VIII 


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I20  INHERITANCE    IN    POULTRY. 


Plate  IX. 

Pig.  26. — Black  Cochin  Bantam,  9  129.  Shows  short  tail  and  heavily  booted  feet.  The 
mother  of  the  barred  bird,  fig.  27.     (H.  A.  H.) 

Fig.  27. — First  hybrid,  rf  365,  between  Black  Cochin  Bantam  (fig.  26)  and  White  Leghorn 
{cf.  fig.  15).  Note  barred  plumage  coloration,  red  earlobe,  and  booted  feet. 
(H.  A.  H.) 

Pig.  28.— Bufif  Cochin  Bantam,  cT  545-  ^'^''^  short  tail,  heavily  booted  feet,  red  earlobe, 
and  single  comb. 


PLATE    IX. 


122  INHERITANCE   IN   POULTRY. 


Plate  X. 

Fig.  29. — Tosa  fowl,  (^  ia,  imported  from  Japan.      Long  tail  feathers  had  been  recently 
pulled  out. 

Fig.  30. — Tosa  fowl,  9  2A,  imported  from  Japan.     Note  the  light  shafting. 

Fig.  31. — Tosa  fowl,  cf  3A,  "Admiral  Togo,"  son  of  ia  and  2A.     Photographed  Septem- 
ber 7,  1905.     Note  length  of  tail.     (H.  A.  H.) 

Fig.  32. — White  Cochin  Bantam,  9  iS^-     This  bird  was  crossed   with  fig.  29  and  gave 
hybrids  represented  on  plate  XI. 


PLATE  X. 


32 


124  INHERITANCE   IN    POULTRY, 


PI.ATE  XI. 

Fig.  33.  First  generation  hybrid,  $  58,  between  White  Cochin  (fig.  32)  and  Tosa  fowl 
(fig.  29).  Note  a  slight  broadening  of  shaft  stripe  as  compared  with  female 
Tosa  fowl. 

Fig.  34, — First  hybrid,  rf  53,  between  White  Cochin  and  Tosa  fowl  (fig.  29).  Note  white 
barring  on  feathers,  and  long  tail.     (H.  A.  H.) 

Fig.  35. — First  hybrid,  cf  95,  between  White  Cochin  and  Tosa  fowl,  younger  brother  to 
fig.  34.     Note  barring  and  growth  of  saddle  and  tail  feathers.     (H.  A.  H.) 

Fig.  36. — Second  generation  hybrid,  9  312,  between  White  Cochin  and  Tosa  fowl.  Note 
pure  white  plumage  color,  like  Cochin  grandmother,  fig.  32,  combined  with 
long  tail  of  Tosa,  fig.  30.     (H.  A.  H.) 


PLATE  XI 


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126  INHERITANCE    IN   POULTRY. 


Plate  XII. 

Fig.  37. — Plumage  chart  of  F,  (White  Cochiu  X  Tosa),  9  58.  at  about  5  months,  pi,  to 
of  head  ;  2,  hackle  ;  3,  middle  of  back  ;  4,  throat ;  5,  breast ;  6,  middle  tail ; 
7,  saddle ;  8,  wing,  secondary. 

Fig.  37a.— Plumage  chart  of  F,  (White  Cochin  X  Tosa),  cf  53,  at  about  5  months.  Signifi- 
cation of  figures  same  as  in  fig.  37.     Shows  barring  of  feathers. 

Fig.  38. — Second  hybrid  generation  (White  Cochin  X  Tosa),  J^  315.  Note  reappearance 
of  pure  white  like  Cochin  grandmother  (fig.  32,  plate  X)  ;  form  intermediate, 
feet  booted.     (H.  A.  H.) 


37= 


37 


128  INHERITANCE    IN    POX"'LTRY. 


Plate  xill. 

Fig.  39. — Jungle  fowl,  9  2.  Taken  after  death  to  show  shafting  on  breast,  nape,  back, 
and  wing  coverts. 

Fig.  40. — First  ^reneration  hybrid,  (^  358,  between  Dark  Brahma  (fig.  19,  plate  V)  and  Tosa 
fowl  (fig.  29).  Note  white  laced  hackles  and  saddles,  vulture  hock,  boot, 
and  pea  comb  of  Brahma  and  white  earlobe  and  elongated  head  of  Tosa. 
(H.  A.  H.) 


PLATE    XII 


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130  INHERITANCE   IN   POULTRY. 


Plate  XIV. 

Pic.  41. — Frizzle  fowl,  cT  ^5-  Note  rose  comb  and  feathers  that  turn  forward,  forming  a 
ruff  on  the  neck.  On  the  exposed  vanes  of  the  upper  secondaries  the  twist- 
ing of  the  barbs  may  be  seen. 

Fig.  42. — Frizzle  fowl,  9  i8a.  Note  extreme  curling  of  feathers,  the  absence  of  barbs  on 
part  of  the  secondaries,  leaving  the  shaft  quite  naked,  and  the  absence  of 
plumage  on  the  back  of  the  head. 

Pig.  43. — Silky  fowl,  (^f  21A.  Note  single  comb,  small  crest,  the  downy  condition  of  the 
contour  feathers,  and  the  elongated  aud  disconnected  barbs  of  the  wing 
secondaries  and  tail  feathers. 

Pig.  44. — First  hybrid  between  Frizzle  and  Silky,  cf  219.  Note  the  white  plumage,  rose 
comb,  trace  of  crest,  frizzled  feathers  (ruff  !),  and  absence  of  elongated  barbs 
on  the  wing,  secondaries,  or  other  evidence  of  silkiness.  The  booted  feet  and 
extra  toe  are  derived  from  the  Silky.     (H.  A.  H.) 


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132  INHERITANCE   IN   POULTRY. 


PI.ATE  XV. 

Fig.  45. — Runipless  Game,  9  49- 

Fig.  46. — Ruinpless  Game,  J"'  117.  The  hackles  and  saddles  and  wing  bars  are  red  ;  other- 
wise the  plumage  is  largely  black.     (H.  A.  H.) 

Fig.  47. — First  hybrid  between  White  Leghorn  {cf.  fig.  15,  plate  IV)  and  Rumpless  Game, 
(J' 516.  Note  dominance  of  white  (except  for  a  trace  of  red  on  the  wing 
coverts)  and  long  tail.  The  comb  is  intermediate  between  that  of  a  Game 
and  that  of  a  White  Leghorn.     (H.  A.  H.) 


PLATE  XV. 


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134  INHERITANCE   IN   POULTRY. 


Plate  XVI. 

Fig.  48. — Head  of  second  generation  Minorca  X  Polish  hybrid,  (J*  474.  Shows  last  term 
of  series,  beginning  with  fig.  50  and  passing  through  fig.  49,  of  reduction 
of  median  component  of  Y  comb,  leaving  only  two  papillae  remaining. 
(H.  A.  H.) 

Fig.  49. — Head  of  second  generation  Minorca  X  Polish  hybrid.  Shows  middle  term  of 
series  passing  from  Y  comb  to  V  comb.  The  median  portion  of  the  comb  is 
represented  by  a  carunculated  mass  at  the  base  of  the  papillae.     (H.  A.  H.) 

Fig,  50.—  Head  of  second  generation  Minorca  X  Polish  hybrid,  ^f  259.  Shows  beginning 
degeneration  of  median  component  of  Y  comb,  which  ends  in  the  V  comb 
(fig.  48).     (H.  A.  H.) 

Fig.  51. — Head  of  second  generation  Minorca  X  Polish  hybrid.  Shows  2  pairs  of  papillae, 
high  nostrils  and  rudimentary  crest,  indicating  that  the  first  two  character- 
istics are  independant  of  the  third.     H.  A.  H.) 

Fig.  52- — Dorsal  view  of  head  of  (Minorca  X  Polish)  X  Minorca  hybrid.  Shows  Y  comb 
in  which  the  median  component  extends  between  the  arms  of  the  Y,  the 
whole  resembling  a  pea  comb.     (H.  A.  H.) 


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136  INHKRITANCE   IN   POrLTRY. 


Plate  XVII. 

Fig.  53. — First  generation  hybrid  between  Silky  and  Jungle  fowl,  (^  156.  Shows  domi- 
nance of  Jungle-fowl  plumage  color  and  the  extra  toe  and  crest  of  the  Silky. 
(H.  A.  H.') 

Fig.  54. — First  generation  hybrid  between  White  Leghorn  and  Rose  Con.b  Black  Mi- 
norca, 9  1 38.  One  of  the  two  birds  that  exhibit  the  blue,  Andalusian  type 
of  coloration,  all  others  being  white.     (H.  A.  H.) 


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